Littérature scientifique sur le sujet « Cathodes hybrides »
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Articles de revues sur le sujet "Cathodes hybrides"
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Dolphijn, Guillaume, Fernand Gauthy, Alexandru Vlad et Jean-François Gohy. « High Power Cathodes from Poly(2,2,6,6-Tetramethyl-1-Piperidinyloxy Methacrylate)/Li(NixMnyCoz)O2 Hybrid Composites ». Polymers 13, no 6 (23 mars 2021) : 986. http://dx.doi.org/10.3390/polym13060986.
Texte intégralRésumé :
Lithium-ion batteries are today among the most efficient devices for electrochemical energy storage. However, an improvement of their performance is required to address the challenges of modern grid management, portable technology, and electric mobility. One of the most important limitations to solve is the slow kinetics of redox reactions associated to inorganic cathodic materials, directly impacting on the charging time and the power characteristics of the cells. In sharp contrast, redox polymers such as poly(2,2,6,6-tetramethyl-1-piperidinyloxy methacrylate) (PTMA) exhibit fast redox reaction kinetics and pseudocapacitors characteristics. In this contribution, we have hybridized high energy Li(NixMnyCoz)O2 mixed oxides (NMC) with PTMA. In this hybrid cathode configuration, the higher voltage NMC (ca. 3.7 V vs. Li/Li+) is able to transfer its energy to the lower voltage PTMA (3.6 V vs. Li/Li+) improving the discharge power performances and allowing high power cathodes to be obtained. However, the NMC-PTMA hybrid cathodes show an important capacity fading. Our investigations indicate the presence of an interface degradation reaction between NMC and PTMA transforming NMC into an electrochemically dead material. Moreover, the aqueous process used here to prepare the cathode is also shown to enable the degradation of NMC. Indeed, once NMC is immersed in water, alkaline surface species dissolve, increasing the pH of the slurry, and corroding the aluminum current collector. Additionally, the NMC surface is altered due to delithiation which enables the interface degradation reaction to take place. This reaction by surface passivation of NMC particles did not succeed in preventing the interfacial degradation. Degradation was, however, notably decreased when Li(Ni0.8Mn0.1Co0.1)O2 NMC was used and even further when alumina-coated Li(Ni0.8Mn0.1Co0.1)O2 NMC was considered. For the latter at a 20C discharge rate, the hybrids presented higher power performances compared to the single constituents, clearly emphasizing the benefits of the hybrid cathode concept.
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Huang, Kevin. « Performance of Several Excellent Oxide-Based Intercalation Cathodes for Aqueous Zn-Ion Batteries ». ECS Meeting Abstracts MA2023-01, no 5 (28 août 2023) : 921. http://dx.doi.org/10.1149/ma2023-015921mtgabs.
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Aqueous Zn-ion batteries (ZIBs) have garnered significant interest in recent years due to their advantages in safety, cost, and energy density, which make them suitable for large-scale stationary energy storage. Cathode materials have been a primary research focus in the early stage of ZIBs development since they are widely deemed a limiting factor to the performance. In general, good ZIB cathode materials are found in oxides with layered and open framework structures, and inorganic/organic hybrids, and follow mechanisms of “intercalation”, “conversion” or a combination of both to store Zn2+ and H+ during discharge. However, dissolution of these cathodes into aqueous electrolytes has been a major cause of the performance degradation of aqueous ZIBs. In this presentation, we first show our fundamental understanding of cathode dissolution mechanisms and development of engineering solutions to address the dissolution and instability issues. We then show through several examples how specially engineered V-oxides based cathodes achieve better dissolution resistance and performance stability using aqueous Zn(OTf)2 and ZnSO4 electrolytes as examples. We expect that the insights in this presentation will advance the understanding of dissolution mechanisms and provide design principles for better cathode materials.
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Choudhury, Soumyadip, Marco Zeiger, Pau Massuti-Ballester, Simon Fleischmann, Petr Formanek, Lars Borchardt et Volker Presser. « Carbon onion–sulfur hybrid cathodes for lithium–sulfur batteries ». Sustainable Energy & ; Fuels 1, no 1 (2017) : 84–94. http://dx.doi.org/10.1039/c6se00034g.
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Wong, Min Hao, Zixuan Zhang, Xianfeng Yang, Xiaojun Chen et Jackie Y. Ying. « One-pot in situ redox synthesis of hexacyanoferrate/conductive polymer hybrids as lithium-ion battery cathodes ». Chemical Communications 51, no 71 (2015) : 13674–77. http://dx.doi.org/10.1039/c5cc04694g.
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Edwards, Sean L., Ronen Fogel, Kudzai Mtambanengwe, Chamunorwa Togo, Richard Laubscher et Janice L. Limson. « Metallophthalocyanine/carbon nanotube hybrids : extending applications to microbial fuel cells ». Journal of Porphyrins and Phthalocyanines 16, no 07n08 (juillet 2012) : 917–26. http://dx.doi.org/10.1142/s1088424612501027.
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Pioneering work by Nyokong and others have highlighted the potential benefits for improved electron transfer processes and catalysis of hybrid configurations of metallophthalocyanines with carbon nanotubes. Here we examine the practical application of such hybrid configurations in an Enterobacter cloacae microbial fuel cell. Electrochemical investigations at glassy carbon electrodes (GCEs) showed that FePc and FePc :multiwalled carbon nanotube (MWCNT) hybrid surface modifications display significant oxygen reduction reaction electrocatalytic properties compared to either MWCNT-modified or bare GCE surfaces throughout acidic- to moderately-alkaline pHs. Significant stabilization of the current response at FePc :MWCNT surfaces are notable throughout the pH range, compared to GCE surfaces modified with FePc alone. Corresponding results were obtained for surface modifications of bare carbon paper (BCP) cathodes in a microbial fuel cell where power density increases were observed in the order: Pt > FePc :MWCNT > FePc > MWCNT > BCP. A synergistic combination of simple treatments such as increased ionic strength (300 mM NaCl ), temperature (35 °C), and agitation of the anode chamber in this MFC configuration increased the power density to 2.5 times greater than that achieved at platinised cathode configurations under non-optimised conditions, achieving peak power densities of 212 mW.m-2. The long-term stability of the MFC was assessed over 55 days. Surprisingly, the majority of signal loss over extended MFC operation was attributed, in this study, to fouling of the Nafion® PEM membrane rather than either leaching/fouling of the catalysts from the electrodes or nutrient depletion in the anode over the time periods examined.
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Cuentas-Gallegos, A. K., R. Vijayaraghavan, M. Lira-Cantú, N. Casañ-Pastor et P. Gómez-Romero. « Materiales híbridos basados en fosfato de vanadilo y polímeros conductores como cátodos en baterías reversibles de litio ». Boletín de la Sociedad Española de Cerámica y Vidrio 43, no 2 (30 avril 2004) : 429–33. http://dx.doi.org/10.3989/cyv.2004.v43.i2.545.
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Hu, Ting, Lie Chen, Kai Yuan et Yiwang Chen. « Amphiphilic fullerene/ZnO hybrids as cathode buffer layers to improve charge selectivity of inverted polymer solar cells ». Nanoscale 7, no 20 (2015) : 9194–203. http://dx.doi.org/10.1039/c5nr01456e.
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An, Meichun, Mohammad Abdul Aziz et Yong Lak Joo. « Hybridization of Mesoporous Carbon and Iron Oxide for Better Mitigation of Polysulfide Shuttling in Li-S Batteries ». ECS Meeting Abstracts MA2022-01, no 7 (7 juillet 2022) : 660. http://dx.doi.org/10.1149/ma2022-017660mtgabs.
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With a higher theoretical capacity, lithium-sulfur (Li-S) batteries have been considered as promising candidates for next-generation batteries. Due to the non-conducting nature of sulfur, however, lithium-sulfur batteries tend to exhibit poor performance at a high current rate (C-rate). Here we demonstrate that Fe3O4, synthesized from precursor iron (III) acetylacetonate (AAI), and mesoporous carbon material, Ketjen Black (KB), can be synergistically combined to enhance the electrochemical performance of lithium-sulfur batteries substantially. Instead of adding commercial magnetite particles into Li-S cathodes, iron oxides are synthesized and imbedded into KB from a precursor, AAI, through thermal treatments in air and Ar. The sulfur, then, is incorporated into iron oxides/KB hybrids by melting at an elevated temperature. With air-controlled electrospray as the processing method, sulfur embedded iron oxides/KB, poly(acrylic acid), and rGO sheets are mixed and directly deposited onto the carbon-coated aluminum collector, to employ as the Li-S battery cathode. X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) studies confirm that Fe3O4 and iron carbide (Fe3C) are synthesized from the precursor, AAI, embedded in mesoporous carbon materials, and reducing the charge transfer resistance of batteries. The rate-capability tests show that systems with KB/Fe3O4 can achieve enhanced performance compared to batteries without iron oxides, especially at high C-rates. With 14 wt % of solid materials as iron oxides and iron carbide, batteries exhibit 750 mAh/g at 2C discharge/charge rates, which is 83% higher compared to systems without iron oxides. However, incorporated via 250 °C for 0.5 hr in air and 850 °C for 2 hr in Ar, the composite of KB/Fe3O4/Fe3C induces irreversible side reactions during the initial charging process, which causes a huge difference in capacity between the first and the second cycle. To achieve an optimal status with improved rate capability and acceptable initial charging time, we modify the thermal treatments and thus increase the proportion of Fe3O4 in the mixture. According to the postmortem analysis, cathodes with iron oxides can interact with soluble polysulfides strongly and alleviate the polysulfide shuttle effect significantly, compared with those without Fe3O4. Such enhanced rate capability by KB/Fe3O4 (synthesized) over KB only or KB/Fe3O4 (commercial) systems suggests that the incorporation of iron oxides can play an important role in improving the electrical conductivity of cathode and mitigating polysulfide shuttle effect. Figure 1
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Cuentas-Gallegos, A. K., M. R. Palacín, M. T. Colomer, J. R. Jurado et P. Gómez-Romero. « Estudios de materiales de cátodos híbridos y ánodos vítreos. Caracterización en celdas de ion litio ». Boletín de la Sociedad Española de Cerámica y Vidrio 41, no 1 (28 février 2002) : 115–21. http://dx.doi.org/10.3989/cyv.2002.v41.i1.708.
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Yang, Yiqun, Kayla Strong, Gaind P. Pandey et Lamartine Meda. « Nanostructured V2O5/Nitrogen-doped Graphene Hybrids for High Rate Lithium Storage ». MRS Advances 3, no 60 (2018) : 3495–500. http://dx.doi.org/10.1557/adv.2018.424.
Texte intégralRésumé :
ABSTRACTVanadium Pentoxide (V2O5) has been identified as a potential cathode material owning to its high specific capacity, theoretically, 441 mAh g-1 for 3Li+ ions insertion/extraction. However, the intrinsic drawbacks of V2O5, i.e. structural instability and poor electronic and ionic conductivity, greatly inhibit its application as a cathode. Here, we report a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal reaction to synthesize V2O5 nanoclusters. Unique aggregated fiber structure was obtained after annealing. To achieve a porous structure and increase the conductivity, nitrogen-doped Graphene (NG) suspended in ethylene glycol was added to the reaction mixture. The obtained spherical V2O5 nanoparticles and NG sheets were randomly dispersed in the matrix of the V2O5 spheres. As a cathode material for lithium-ion batteries, the V2O5/NG hybrids demonstrate better rate performance compared to the bundle-like V2O5 fibers, delivering higher specific capacity of ∼ 300 and 150 mAh g-1 at a rate of C/10 and 5C, respectively. The enhanced performance in lithium storage are attributed to the synergistic effect of the nanostructured V2O5/NG composites.
Thèses sur le sujet "Cathodes hybrides"
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Adjez, Yanis. « Stimulation of Electrocatalytic Reduction of Nitrate by Immobilized Ionic Liquids ». Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS337.pdf.
Texte intégralRésumé :
La pollution de l'eau par les nitrates représente un défi environnemental majeur et constitue l'une des dix violations les plus courantes de la qualité de l'eau dans le monde. Ce défi offre une opportunité pour l'économie circulaire, car l'électrolyse des nitrates a été proposée comme une méthode durable pour la valorisation des effluents contaminés par les nitrates grâce à la production décentralisée et simultanée d'ammoniac (un produit chimique de base). En particulier, la réduction électrochimique des nitrates (REN) est une stratégie prometteuse et durable pour résoudre le problème critique de la pollution des sources d'eau par les nitrates. Plusieurs matériaux abondants sur Terre, tels que le cuivre et l'étain, ont été proposés comme matériaux électrocatalytiques adaptés pour la REN. Jusqu'à présent, la plupart des études électrochimiques fondamentales ont été menées dans des conditions potentiostatiques. En revanche, cette étude présente une évaluation de la REN dans des conditions galvanostatiques pour atteindre des conditions opérationnelles plus représentatives pour des systèmes ingénierisés de plus grande envergure. Cependant, cela provoque l'apparition de la réaction concomitante de dégagement de l'hydrogène (HER), qui se produit à un potentiel thermodynamique similaire à celui de la REN. Ainsi, l'efficacité faradique de la REN diminue considérablement dans des conditions galvanostatiques réalistes en raison de la concurrence avec la HER. Ce projet aborde ce défi fondamental en électrocatalyse et propose une nouvelle stratégie basée sur l'immobilisation de molécules ioniques à base d'imidazolium sur la surface de la cathode pour inhiber sélectivement la HER et améliorer la REN. Notamment, cette recherche explore une gamme de matériaux de cathodiques hybrides, y compris des électrodes à base de carbone et de métal sous forme de plaques 2D et de mousses 3D, reconnues pour leur potentiel dans les applications réelles de la REN. Le succès de l'immobilisation de la couche organique ionique sur les cathodes a été confirmé par différentes techniques de caractérisation physico-chimiques et par une évaluation subséquente de l'activité et de la sélectivité électrocatalytiques, démontrant une sélectivité et une efficacité faradique améliorées pour la production d'ammoniac sur les cathodes hybrides, deux fois supérieures à celles du matériau d'électrode nu pour la REN dans les mêmes conditions expérimentalesNitrate pollution in water represents a significant environmental challenge and is one of the top ten most common water quality violations worldwide. This challenge offers an opportunity for the circular economy as nitrate electrolysis has been suggested as a sustainable method for valorization of nitrate-contaminated effluents by simultaneous decentralized ammonia production (a commodity chemical). In particular, the electrochemical reduction of nitrate (ERN) is a promising and sustainable strategy for addressing the critical issue of nitrate pollution in water sources. Several earth abundant materials such as copper and tin have been suggested as suitable electrocatalytic materials for ERN. Mostly fundamental electrochemical studies under potentiostatic conditions are reported so far. In contrast, this study presents ERN evaluation under galvanostatic conditions for achieving more representative operational conditions for larger engineered systems. However, this provokes the appearance of the concomitant hydrogen evolution reaction (HER), which takes place at a similar thermodynamic potential than ERN. Thus, faradaic efficiency for ERN significantly diminishes under realistic galvanostatic conditions due to the competition with HER. This project addresses this fundamental challenge in electrocatalysis and proposes a novel strategy based on the immobilization of imidazolium-based ionic molecules on the surface of the cathode to selectively inhibit HER and enhance ERN. Notably, this research explores a range of hybrid cathode materials, including 2D plate and 3D foam carbon- and metal-based electrodes, which are recognized for their potential in real world applications for ERN. The success of the ionic organic layer immobilization onto the cathodes was confirmed through different physicochemical characterization techniques and subsequent electrocatalytic activity and selectivity evaluation, which demonstrated an enhanced selectivity and faradaic efficiency for ammonia production on hybrid cathodes twice as much as the bare electrode material for ERN under the same experimental conditions
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Moraw, Franz Christian. « Hybrid PEM fuel cell : redox cathode approach ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/7720.
Texte intégralRésumé :
The proton exchange membrane fuel cell (PEMFC) is considered to be a
promising power device with a broad range of applications. However, there are still a
number of challenges especially concerning performance, cost, and reliability of these
systems. The redox flow battery utilizes fundamentally simpler chemistry, but has
limitations in terms of membranes/materials used in system construction and in terms of
redox regeneration requirements.
The hybridization of a PEMFC anode with a redox flow battery cathode,
replacing the limiting oxygen electrode, leads to both advantages and compromises in
performance. Although there are improvements in kinetics, cell and systems design, and
cost, there are restrictions imposed by the regeneration method and membrane
contamination. In this work, the Fe³⁺/Fe²⁺ redox fuel cell cathode is characterized over a
range of electrolyte concentrations, operating conditions, and electrode materials. A
Fe³⁺/Fe²⁺ simulated bio-electrolyte and a
simple electrolyte catholyte are studied using
CV and ETS to determine kinetic parameters for the electrolyte cathode redox couple,
while a prototype single cell fuel cell is used to demonstrate actual fuel cell performance.
Electrochemical data shows the effect of ferric ion complexation! polymerization
on the operation of both electrolyte systems. The results show that the heterogeneous
electron transfer rate constant and diffusion coefficient as well as interface properties all
increase with the ratio of total anion species (S0₄²⁻,HS0₄⁻)to ferric species. Fuel cell
testing showed no significant difference in performance between the two systems
opening up various possibilities for redox species regeneration. Improvements are also
achieved through optimization of cathode materials and operating conditions.
This hybrid system, part of a strategic NSERC grant (Novel biofuel cell - methane
reforming reactor system for electricity generation, #GHGPJ 269967 — 03)(1), showed
promising performance even though components such as the membrane were not
optimized. Power densities of greater than 0.25 W/cm² were achieved with no platinum
group metals on the cathode. In addition, the liquid redox cathode eliminates the need for
external humidification and separate cooling for the fuel cell and provides greater design
flexibility. Different aspects of the redox cathode were characterized and showed
opportunity for further performance improvement.
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Osiecki, Tomasz, Colin Gerstenberger, Holger Seidlitz, Alexander Hackert et Lothar Kroll. « Behavior of Cathodic dip Paint Coated Fiber Reinforced Polymer/Metal Hybrids ». Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-175536.
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Increasing mechanical, economic and environmental requirements lead to multi material designs, wherein different classes of materials and manufacturing processes are merged to realize lightweight components with a high level of functional integration. Particularly in automotive industry the use of corresponding technologies will rise in the near future, as they can provide a significant contribution to weight reduction, energy conservation and therefore to the protection of natural resources. Especially the use of continuous fiber reinforced polymers (FRP) with thermoplastic matrices offers advantages for automotive components, due to its good specific characteristics and its suitability for mass production. In conjunction with isotropic materials, such as steel or aluminum, optimized lightweight structures can be produced, whose properties can be easily adapted to the given component requirements.
The present paper deals with the development of innovative hybrid laminates with low residual stresses, made of thin-walled steel sheets and glass fiber reinforced thermoplastic (GFRP) prepregs layers. Thereby the interlaminar shear strength (ILSS) was increased by an optimization of the FRP/metal-interfaces, carried out by examining the influence of several pre-operations like sanding, cleaning with organic solvents and applying primer systems. Based on these findings optimized compound samples were prepared and tested under realistic Cathodic dip paint conditions to determine the influence on the ILSS.
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Gustavsson, Lars-Erik. « Hollow Cathode Deposition of Thin Films ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6925.
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Söderström, Daniel. « Modelling and Applications of the Hollow Cathode Plasma ». Doctoral thesis, Uppsala universitet, Elektricitetslära, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8747.
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This thesis presents experimental and modelling research on atmospheric pressure hollow cathodes and hollow electrodes. Experiments with the hybrid hollow electrode activated discharge (H-HEAD), which is a combination of a hollow cathode and a microwave plasma source, is presented. The experiments show that this source is able to produce long plasma columns in air and nitrogen at atmospheric pressure and at very low gas flow rates. Measurements of the vibrational temperature of the nitrogen molecules are also presented in this thesis. The vibrational temperature is an indication of the electron temperature in the plasma, an important characteristic of the plasma. Modelling work on the hollow cathode at atmospheric pressure with fluid equations is also presented. It is shown that the inclusion of fast and secondary electrons, characteristic of the hollow cathode plasmas, increases the sheath width. The sheath width was found to be of the order of 100 μm. By modelling the plasma as highly collisional by using the drift-diffusion approximation, it was shown that the increase in sheath thickness was larger at lower pressures than at higher pressures. Still, the sheath width can be of the order of 100 μm. A pulsed atmospheric plasma in a hollow electrode geometry was also modelled by the drift-diffusion fluid equations, with the addition of the energy equation for electrons. Rate and transport coefficients for the electrons were calculated from the solution to the Boltzmann equation as functions of mean electron energy. The dynamics of the plasma at pulse rise time showed large electron density and mean energy peaks at the cathode ends, but also that these quantities were enhanced at the centre of the discharge, between the cathode plates.
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Ezzedine, Mariam. « Fabrication of hierarchical hybrid nanostructured electrodes based on nanoparticles decorated carbon nanotubes for Li-Ion batteries ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX105/document.
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Cette thèse est consacrée à la fabrication ascendante (bottom-up) de matériaux nanostructurés hybrides hiérarchisés à base de nanotubes de carbone alignés verticalement (VACNTs) décorés par des nanoparticules (NPs). En fonction de leur utilisation comme cathode ou anode, des nanoparticules de soufre (S) ou silicium (Si) ont été déposées. En raison de leur structure unique et de leurs propriétés électroniques, les VACNTs agissent comme une matrice de support et un excellent collecteur de courant, améliorant ainsi les voies de transport électroniques et ioniques. La nanostructuration et le contact du S avec un matériau hôte conducteur améliore sa conductivité, tandis que la nanostructuration du Si permet d'accommoder plus facilement les variations de volume pendant les réactions électrochimiques. Dans la première partie de la thèse, nous avons synthétisé des VACNTs par une méthode de dépôt chimique en phase vapeur (HF-CVD) directement sur des fines feuilles commerciales d'aluminium et de cuivre sans aucun prétraitement des substrats. Dans la deuxième partie, nous avons décoré les parois latérales des VACNTs avec différents matériaux d'électrode, dont des nanoparticules de S et de Si. Nous avons également déposé et caractérisé des nanoparticules de nickel (Ni) sur les VACNTs en tant que matériaux alternatifs pour l'électrode positive. Aucun additif conducteur ou aucun liant polymère n'a été ajouté à la composition d'électrode. La décoration des nanotubes de carbone a été effectuée par deux méthodes différentes: méthode humide par électrodéposition et méthode sèche (par dépôt physique en phase vapeur (PVD) ou par CVD). Les structures hybrides obtenues ont été testées électrochimiquement séparément dans une pile bouton contre une contre-électrode de lithium. A notre connaissance, il s'agit de la première étude de l'évaporation du soufre sur les VACNTs et de la structure résultante (appelée ici S@VACNTs). Des essais préliminaires sur les cathodes nanostructurées obtenues (S@VACNTs revêtus d'alumine ou de polyaniline) ont montré qu'il est possible d'atteindre une capacité spécifique proche de la capacité théorique du soufre. La capacité surfacique de S@VACNTs, avec une masse de S de 0.76 mg cm-2, à un régime C/20 atteint une capacité de 1.15 mAh cm-2 au premier cycle. Pour les anodes nanostructurées au silicium (Si@VACNTs), avec une masse de Si de 4.11 mg cm-2, on montre une excellente capacité surfacique de 12.6 mAh cm-2, valeur la plus élevée pour les anodes à base de silicium nanostructurées obtenues jusqu'à présent. Dans la dernière partie de la thèse, les électrodes nanostructurées fabriquées ont été assemblées afin de réaliser la batterie complète (Li2S/Si) et sa performance électrochimique a été testée. Les capacités surfaciques obtenues pour les électrodes nanostructurées de S et de Si ouvrent la voie à la réalisation d'une LIB à haute densité d'énergie, entièrement nanostructurée, et démontrent le grand potentiel du concept proposé à base d'électrodes nanostructurées hybrides hiérarchiséesThis thesis is devoted to the bottom-up fabrication of hierarchical hybrid nanostructured materials based on active vertically aligned carbon nanotubes (VACNTs) decorated with nanoparticles (NPs). Owing to their unique structure and electronic properties, VACNTs act as a support matrix and an excellent current collector, and thus enhance the electronic and ionic transport pathways. The nanostructuration and the confinement of sulfur (S) in a conductive host material improve its conductivity, while the nanostructuration of silicon (Si) accommodates better the volume change during the electrochemical reactions. In the first part of the thesis, we have synthesized VACNTs by a hot filament chemical vapor deposition (HF-CVD) method directly over aluminum and copper commercial foils without any pretreatment of the substrates. In the second part, we have decorated the sidewalls and the surface of the VACNT carpets with various LIB's active electrode materials, including S and Si NPs. We have also deposited and characterized nickel (Ni) NPs on CNTs as alternative materials for the cathode electrode. No conductive additives or any polymer binder have been added to the electrode composition. The CNTs decoration has been done systematically through two different methods: wet method by electrodeposition and dry method by physical vapor deposition (PVD). The obtained hybrid structures have been electrochemically tested separately in a coin cell against a lithium counter-electrode. Regarding the S evaporationon VACNTs, and the S@VACNTs structure, these topics are investigated for the first time to the best of our knowledge.Preliminary tests on the obtained nanostructured cathodes (S@VACNTs coated with alumina or polyaniline) have shown that it is possible to attain a specific capacity close to S theoretical storage capacity. The surface capacity of S@VACNTs, with 0.76 mg cm-2 of S, at C/20 rate reaches 1.15 mAh cm-2 at the first cycle. For the nanostructured anodes Si@VACNTs, with 4.11 mg cm-2 of Si showed an excellent surface capacity of 12.6 mAh cm-2, the highest value for nanostructured silicon anodes obtained so far. In the last part of the thesis, the fabricated nanostructured electrodes have been assembled in a full battery (Li2S/Si) and its electrochemical performances experimentally tested. The high and well-balanced surface capacities obtained for S and Si nanostructured electrodes pave the way for realization of high energy density, all-nanostructured LIBs and demonstrate the large potentialities of the proposed hierarchical hybrid nanostructures' concept
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Holmes, Steven. « An investigation into the practical and theoretical aspects of hybrid cathodic protection ». Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/12280.
Texte intégralRésumé :
Galvanic anode technology has in recent years come to the fore as a cost-effective method of successfully mitigating the corrosion of reinforcing steel in concrete structures. Developments in the field of cathodic protection have included the introduction of a novel Hybrid anode system, which uses the same sacrificial anode to pass a short-term impressed current before being connected to the steel directly to provide a long-term galvanic current. Galvanic and hybrid technologies are often seen as less powerful solutions in the treatment of reinforcement corrosion, and the test methodologies which determine the efficacy of cathodic protection systems favour impressed current technologies. The work completed has investigated the application of traditional and novel corrosion assessment techniques to laboratory samples to assess the protection offered by the hybrid treatment methodology in both treatment phases. In addition, the response of both galvanic and hybrid anodes to environmental conditions has been recorded and assessed before being discussed in the context of steel protection criteria. Finally, an investigation is presented into the on-site deterioration of commercially pure titanium feeder wire installed as part of the hybrid anode system and potential solutions to the problem have been documented. The research undertaken found that the hybrid anode system is capable of protecting steel in challenging, aggressive environments. This was confirmed by steel corrosion rate and indicative steel potential measurements. The responsive behaviour investigation showed that the current output of galvanic and hybrid anodes responds rapidly to changes in the corrosion risk posed to the steel and that this has a direct effect on anode system lifetimes. An assessment of the polarisation-based protection criteria applied to steel in concrete has found that the standard inhibits the use of responsive behaviour, and that revisions which consider the present risk of steel corrosion by considering the corrosion current resulting from the relative aggressivity of the concrete environment would be more valid in their application. A cathodic protection system based on the concepts of pit re-alkalisation and pH maintenance can fully utilise galvanic anode responsive behaviour. It was discovered that the deterioration of commercially pure titanium feeder wire seen on site installations was due to anodising in the presence of chloride media which had the potential to lead to pitting corrosion. The pitting risk varied depending on the duration of the treatment and proximity to the installed anode. An anodically grown oxide delayed the onset of corrosion in aqueous KBr solution, but did not significantly increase the pitting potential.
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Myalo, Zolani. « Graphenised Lithium Iron Phosphate and Lithium Manganese Silicate Hybrid Cathode Systems for Lithium-Ion Batteries ». University of the Western Cape, 2017. http://hdl.handle.net/11394/6036.
Texte intégralRésumé :
Magister Scientiae - MSc (Chemistry)This research was based on the development and characterization of graphenised lithium iron phosphate-lithium manganese silicate (LiFePO4-Li2MnSiO4) hybrid cathode materials for use in Li-ion batteries. Although previous studies have mainly focused on the use of a single cathode material, recent works have shown that a combination of two or more cathode materials provides better performances compared to a single cathode material. The LiFePO4- Li2MnSiO4 hybrid cathode material is composed of LiFePO4 and Li2MnSiO4. The Li2MnSiO4 contributes its high working voltage ranging from 4.1 to 4.4 V and a specific capacity of 330 mA h g-1, which is twice that of the LiFePO4 which, in turn, offers its long cycle life, high rate capacity as well as good electrochemical and thermal stability. The two cathode materials complement each other's properties however they suffer from low electronic conductivities which were suppressed by coating the hybrid material with graphene nanosheets. The synthetic route entailed a separate preparation of the individual pristine cathode materials, using a sol-gel protocol. Then, the graphenised LiFePO4-Li2MnSiO4 and LiFePO4-Li2MnSiO4 hybrid cathodes were obtained in two ways: the hand milling (HM) method where the pristine cathodes were separately prepared and then mixed with graphene using a pestle and mortar, and the in situ sol-gel (SG) approach where the Li2MnSiO4 and graphene were added into the LiFePO4 sol, stirred and calcined together.
2021-04-30
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El, jouad Zouhair. « Réalisation et caractérisation des cellules photovoltaïques organiques ». Thesis, Angers, 2016. http://www.theses.fr/2016ANGE0022/document.
Texte intégralRésumé :
Cette thèse s’insère dans un projet d’élaboration et de caractérisation des cellules photovoltaïques organiques classiques et inverses, plus précisément il s’agit d’améliorer les performances des cellules via des couches tampons anodiques et cathodiques originales. Nous avons commencé d’améliorer les couches tampons cathodiques avec différents donneurs d’électrons: phtalocyanine de cuivre CuPc, subphtalocyanine SubPc et dérivés de thiophène organiques. Dans le premier cas de donneur d’électrons (CuPc), nous avons mis en évidence l’effet d’une fine couche d’un composé de césium, utilisée comme couche tampon cathodique dans des cellules inverses, sur la collecte des électrons après un traitement thermique. Nous avons montré aussi que la couche tampon cathodique hybride, Alq3 (9nm) / Ca (3nm) améliore les performances des cellules quelque soit le donneur d’électrons et sans nécessité de recuit. Dans le cas de drivés de thiophène, nous avons montré comment la morphologie de surface des couches organiques peut influencer les performances des cellules photovoltaïques organiques. Et dans le cas de SubPc utilisé dans des cellules inverses, nous avons étudié l’effet de la vitesse de dépôt de la couche SubPc sur sa morphologie. Concernant l’amélioration de la couche tampon anodique, nous avons étudié des cellules classiques à base SubPc et du pentathiophene (5T). Après l’optimisation de l’épaisseur des donneurs d’électrons, nous avons montré que la bicouche MoO3 (3 nm) / Cul (1,5 nm) utilisée comme couche tampon anodique, permet d'améliorer les performances des cellules, quelque soit le donneur d’électrons. Dans le cas du SubPc, nous avons obtenu un rendement qui approche de 5%This thesis concerns elaboration and characterization of classical and inverse organic photovoltaic cells, specifically improving the anodic and cathodic buffer layers. We started by improving the cathode buffer layers with different electron donors: copper phthalocyanine CuPc, subphtalocyanine SubPc and thiophene derivatives (BSTV and BOTV). In the first case of electron donor (CuPc), we highlighted the effect of the thin layer of cesium compound, used as a cathodic buffer layer in inverse cells, on the collection of electrons after heat treatment.We have also shown that the hybrid cathodic buffer layer, Alq3 (9 nm) / Ca (3nm) improves the cell performance whatever the electron donor without annealing. In the case of thiophene derivatives, we have shown how the morphology of the organic layers surface can influence the performance of organic photovoltaic cells. In the case of SubPc used in inverse cells, we studied the effect of the deposition rate of the layer on the morphology of SubPc surface.Regarding the improvement of the anodic buffer layers, we investigated those based on the SubPc and pentathiophene (5T) in classical cells. After optimization of the electron donors thickness, we have shown that the bilayer MoO3 (3 nm) / CuI (1.5 nm) used as an anodic buffer layer, improves cell performances, whatever the electron donor. In the case of SubPc, we obtained a efficiency approaching 5%
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Vickers, Simon. « Particle in cell and hybrid simulations of the Z double-post-hole convolute cathode plasma evolution and dynamics ». Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/17874.
Texte intégralRésumé :
The Z-accelerator at Sandia National Laboratories (SNL), is a high-current pulsed power machine used to drive a range of high energy density physics (HEDP) experiments [1]. To achieve peak currents of >20MA, in a rise time of ~100ns, the current is split over four levels of transmission line, before being added in parallel in a double-post-hole convolute (DPHC) and delivered to the load through a single inner magnetically insulated transmission line (MITL). The electric field on the cathode electrode, >107Vm-1, drives the desorption and ionisation of neutral contaminants to form a plasma from which electrons are emitted into the anode-cathode (a-k) gap. The current addition path in the DPHC forms magnetic 'null' regions, across which electrons are lost to the anode, shunting current from the inner MITL and load. In experiment, current losses of >10% have been measured within the convolute; this reduces the power delivered to the load, negatively impacting the load performance, as well as complicating the prediction of the Poynting flux used to drive detailed magneto-hydrodynamic (MHD) simulations [2, 3]. In this thesis we develop 3-dimensional (3D) Particle-in-Cell (PIC) and hybrid fluid-PIC computer models to simulate the plasma evolution in the DPHC and inner MITL. The expected experimental current loss at peak current was matched in simulations where Hydrogen plasma was injected from the cathode elec- trode at a rate of 0.0075mlns-1 (1ml=1015cm-2), with an initial temperature of 3eV. The simulated current loss was driven by plasma penetrating the downstream side of the anode posts, reducing the effective a-k gap spacing and enhancing electron losses to the anode. The current loss at early time (<10MA), was matched in simulations where space-charge-limited (SCL) electron emission was allowed directly from the cathode; to match the loss over the entire current pulse, a delay model is motivated. Here, plasma injection was delayed after the start of SCL emission, based on realistic plasma expansion velocities of ~3cmμs-1. The PIC model, which was necessary to accurately simulate the kinetic behaviour of the lower density plasma and charged particle sheaths, was computationally intensive such that the spatial resolutions achieved in the 3D simulations were relatively poor. With the aim of reducing the computational overhead, allowing finer spatial resolutions to be accessed, we investigate the applicability of hybrid techniques to simulating the cathode plasma in the convolute. Our PIC model was both implemented in the resistive MHD code, Gorgon, where part of the plasma was modelled in the single fluid approximation, and extended to include an inertial two-fluid description of the plasma. The hybrid models were applied to the DPHC simulations, the results from which are used to motivate a three component model; here, the densest part of the convolute plasma is modelled using the single fluid MHD approximation, transitioning to a fully kinetic PIC description of the lower density plasma and charged particle sheaths, linked by a two-fluid description.
Chapitres de livres sur le sujet "Cathodes hybrides"
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Wen, Zhenhai, Suqin Ci et Junhong Chen. « Nanocarbon-Based Hybrids as Cathode Electrocatalysts for Microbial Fuel Cells ». Dans Nanocarbons for Advanced Energy Conversion, 215–32. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527680016.ch8.
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Murugesan, Chinnasamy, Baskar Senthilkumar, Kriti Choudhary et Prabeer Barpanda. « Cobalt–Phosphate-Based Insertion Material as a Multifunctional Cathode for Rechargeable Hybrid Sodium–Air Batteries ». Dans Recent Research Trends in Energy Storage Devices, 35–41. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6394-2_5.
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Godefroidt, Emile, Bjorn Van Belleghem et Tim Soetens. « Effectiveness and Throwing Power of Hybrid Anode Cathodic Protection in Chloride Contaminated Reinforced Concrete ». Dans RILEM Bookseries, 175–86. Cham : Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-75507-1_18.
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Goyal, Megha, et Tapas Kumar Mandal. « Influence of Different Precipitating Agents on the Synthesis of NiMn-LDHs Based Cathode Materials for High Performance Hybrid Devices ». Dans Springer Proceedings in Physics, 187–92. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1971-0_28.
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Parbey, Joseph, Fehrs Adu-Gyamfi et Michael Gyan. « Progress in Cathode Materials for Methanol Fuel Cells ». Dans Methanol Fuel - New Developments, Perspectives and Applications [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1003869.
Texte intégralRésumé :
Methanol fuel cells are the most viable alternative to lithium-ion batteries for portable and other applications. The performance of methanol fuel cell depends in part on the microstructure, contact at the electrode-electrolyte interface, and oxygen reduction reactions (ORR) taking place at the cathode, which requires highly efficient cathode materials. The cathode materials have a significant impact on the performance of methanol fuel cells, making their selection and development an important field of research. This review paper provides a comprehensive overview of the progress made in cathode material selection for methanol fuel cells over the past decade. The development of different classes of cathode materials and cathode support is extensively discussed with particular emphasis on structure and electrochemical properties and performance. Also presented are research challenges and opportunities in developing new cathode materials and future trends. Finally, this review paper provides valuable insights into advancements in cathode material selection for methanol fuel cells, sheds light on hybrid composites support materials, and paves the way for further innovation in the pursuit of efficient and commercially viable methanol fuel cell technologies.
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Rajpurohit, Praveen, et Manaswini Behera. « Light-assisted microbial electrochemical technologies for bioelectricity generation and product recovery ». Dans Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies, 61–80. IWA Publishing, 2024. http://dx.doi.org/10.2166/9781789063813_0061.
Texte intégralRésumé :
With the increase in demand for the improvement of microbial electrochemical technologies (METs) for bioelectricity generation and product recovery, light-assisted METs have developed as an option. The use of light helps in the electrohydrogenesis process at the cathode. Various variants of light-assisted METs employ photosynthetic bacteria/algae, anode and photocathode assembly, and so on. Microbial fuel cells (MFCs) using photosynthetic bacteria, bioelectrodes, and hybrids of photoelectrocatalytic cells (PECs) and MFCs show superior performance compared to individual MFCs. The dye-sensitized solar cell coupling of MFCs helps enhance electrohydrogenesis and H2 production. This book chapter deals with all types of light-assisted METs. The effect of the configuration, electrode material, electrolyte, and physical and chemical factors on the performance of light-assisted METs is discussed. The miniaturizing and stacking of reactors in solar-assisted METs is a current approach showing superior performance. The value-added products formed at the cathodic compartment, carbon-based or H2 gas, are discussed and reported literature compared with the enhanced recovery of existing METs.
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Litovko, Iryna, Alexey Goncharov, Andrew Dobrovolskyi et Iryna Naiko. « The Emerging Field Trends Erosion-Free Electric Hall Thrusters Systems ». Dans Plasma Science and Technology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99096.
Texte intégralRésumé :
The Hall-type accelerator with closed Hall current and open (that is unbounded by metal or dielectric) walls was proposed and considered both theoretically and experimentally. The novelty of this accelerator is the use of a virtual parallel surface of the anode and the cathode due to the principle of equipotentialization of magnetic field lines, which allows to avoid sputtering of the cathode surface and preserve the dynamics of accelerated ions. The formation of the actual traction beam should be due to the acceleration of ions with the accumulated positive bulk charge. A two-dimensional hybrid model in cylindrical coordinates is created in the framework of which the possibility of creation a positive space charge at the system axes is shown. It is shown that the ions flow from the hump of electrical potential can lead to the creation of a powerful ion flow, which moves along the symmetry axis in both sides from the center.
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M. Orona-Hinojos, Jesus. « Innovative Double Cathode Configuration for Hybrid ECM + EDM Blue Arc Drilling ». Dans Drilling Technology. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97547.
Texte intégralRésumé :
Electrical discharge machining is a machining method generally used for machining hard metals, those that would be high cost or have poor performance to machine with other techniques using, e.g., lathes, drills, or conventional machining. Therefore, also known as thermal processes like EDM, Plasma or Laser cutting can be used in drilling operations with poor metallurgical quality on cutting edge and will be necessary complement with other processes such as electrochemical machining (ECM). Both ECM and EDM processes use electrical current under direct-current (DC) voltage to electrically power the material removal rate (MRR) from the workpiece. However in ECM, an electrically conductive liquid or electrolyte is circulated between the electrode(s) and the workpiece for permitting electrochemical dissolution of the workpiece material. While the EDM process, a nonconductive liquid or dielectric is circulated between the cathode and workpiece to permit electrical discharges in the gap there between for removing the workpiece material. Both are principle too different, EC using an electrical conductive and ED using a dielectric medium. But exist a way that can to do a combination of Pulsed EC + ED Simultaneous and allowing the coexist both process, in a semidielectric medium, where both condition exist in the same time, therefore in this hybrid is possible create a tooling device dual cathode for drilling process with promissory advantages fast hole for this innovative hybrid ECDM Simultaneous, this hybrid it’s knew as blue arc drilling technology.
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Arif, Khizra, Abdul Shakoor, Muhammad Awais, Marvi Dashi, Behram Khan Ajat Khel, Bentham Science Publisher Sami Ur Rehman, Khansa Masood, Farah Hussain, Waheed Alam et Muhammad Atif. « Graphene-based Materials for Electrochemical Energy Storage Devices-EESDs ; Opportunities and Future Perspective ». Dans The 2-Dimensional World of Graphene, 160–76. BENTHAM SCIENCE PUBLISHERS, 2024. http://dx.doi.org/10.2174/9789815238938124010011.
Texte intégralRésumé :
The material's exciting properties, which have substantially expanded the field of study, include its enormous surface area, outstanding electrical conductivity, extreme thinness, amazing electron kinesis, and cutting-edge mechanical control. These topographies are largely active for various energy-storage devices (EESDs) such as supercapacitors, hybrid cathode and anode materials, lithium-sulfur batteries, lithiumion batteries, lithium-oxygen batteries, and sodium-ion batteries. The scalability, stability, and uniformity of nanomaterials made of carbon are essential for the development of graphene-based energy storage devices.
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Mohammadi, Arash. « Hybrid nanomaterials of hollow carbon spheres as cathode materials ». Dans Nanostructured Lithium-ion Battery Materials, 87–109. Elsevier, 2025. http://dx.doi.org/10.1016/b978-0-443-13338-1.00024-1.
Texte intégralActes de conférences sur le sujet "Cathodes hybrides"
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Major, K., G. Brisard et J. Veilleux. « Lithium Iron Phosphate Coatings Deposited by Means of Inductively-Coupled Thermal Plasma ». Dans ITSC2015, sous la direction de A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen et C. A. Widener. ASM International, 2015. http://dx.doi.org/10.31399/asm.cp.itsc2015p0566.
Texte intégralRésumé :
Abstract Lithium-ion batteries have high energy efficiency and good cycling life and are considered as one of the best energy storage device for hybrid and/or electrical vehicle. Still, several problems must be solved prior to a broad adoption by the automotive industry: energy density, safety and costs. To enhance both energy density and safety, the current study aims at depositing binder-free cathode materials using inductively-coupled thermal plasma. In a first step, lithium iron phosphate LiFePO4 powders are synthesized in an inductively-coupled thermal plasma reactor and dispersed in a conventional polyvinylidene fluoride (PVDF) binder. Then, binder-free LiFePO4 coatings are directly deposited onto nickel current collectors by solution precursor plasma spraying (SPPS). These plasma-derived cathodes (with and without PVDF binder) are assembled in button cells and tested. Under optimized plasma conditions, cyclic voltammetry shows that the electrochemical reversibility of plasma-derived cathodes is improved over that of conventional sol-gel derived LiFePO4 cathodes. Further results related to the substitution of iron with manganese in the SPPS precursors (LiMPO4, where M = Fe or Mn) are discussed.
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Tucker, David, Larry Lawson, Thomas P. Smith et Comas Haynes. « Evaluation of Cathodic Air Flow Transients in a Hybrid System Using Hardware Simulation ». Dans ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97107.
Texte intégralRésumé :
Effective control of cathode airflow in a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system is critical to thermal management of a fuel cell stack. Hybrid fuel cell turbine designs often incorporate the use of a valved hot air bypass in parallel with the cathode flow to divert a portion of the compressor effluent around the fuel cell system. The primary objective of this valve in the early development of hybrid power systems was to facilitate system startup. From a system controls perspective, the hot air bypass offers the means to balance and manipulate the level of airflow supplied to the fuel cell stack at a minimal efficiency penalty. Manipulation of this valve has a significant impact on stack performance and reliability, as well as cathodic exhaust airflow conditions. Since the turbine is directly coupled to the fuel cell subsystem through the cathode airflow, non-linear effects are propagated through the system components in response to any hot air bypass valve change. The effect of cathode flow transients on hybrid system performance has been evaluated though the manipulation of a hot air bypass valve on a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). A brief overview of this experimental facility is provided and has been described in more detail previously. Open loop experiments were conducted using the facility, where a perturbation was made to the hot air bypass flow and turbine speed was allowed to change in response. The impact of the transients to both fuel cell and turbine performance are discussed.
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Pezzini, Paolo, Sue Celestin et David Tucker. « Control Impacts of Cold-Air Bypass on Pressurized Fuel Cell Turbine Hybrids ». Dans ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2014 8th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fuelcell2014-6523.
Texte intégralRésumé :
A pressure drop analysis for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide means of evaluating risk mitigation strategies. The cold air bypass in the Hyper facility directs compressor discharge flow to the turbine inlet duct, bypassing the fuel cell and exhaust gas recuperators in the system. This valve reduces turbine inlet temperature while reducing cathode airflow, but significantly improves compressor surge margin. Regardless of the reduced turbine inlet temperature as the valve opens, a peak in turbine efficiency is observed during characterization of the valve at the middle of the operating range. A detailed experimental analysis shows the unusual behavior during steady state and transient operation, which is considered a key point for future control strategies in terms of turbine efficiency optimization and cathode airflow control.
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Magistri, Loredana, Mario L. Ferrari, Alberto Traverso, Paola Costamagna et Aristide F. Massardo. « Transient Analysis of Solid Oxide Fuel Cell Hybrids : Part C — Whole-Cycle Model ». Dans ASME Turbo Expo 2004 : Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53845.
Texte intégralRésumé :
A Solid Oxide Fuel Cell-Hybrid System is mainly composed of three parts: the stack, the anodic recirculation system with fuel feeding, and the cathodic side (air side) where turbomachinery and heat exchangers are installed. In Part A of this work the transient models of the fuel cell are described, while in Part B the anodic side is investigated. Many previous studies have been carried out on the cathodic side at the Thermochemical Power Group facility to simulate the transient behavior of the main components such as compressors, expanders and heat exchangers. In this paper attention is focused on the integration of the transient models of the hybrid system components. Following the on and off-design analysis of the SOFC-HS the transient response of the system from an electrochemical, fluid dynamic and thermal point of view has been studied at several operating conditions.
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Lambruschini, Fabio, Mario L. Ferrari, Alberto Traverso et Luca Larosa. « Emergency Shutdown Management in Fuel Cell Gas Turbine Hybrid Systems ». Dans ASME Turbo Expo 2014 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25432.
Texte intégralRésumé :
A real-time dynamic model representing the pressurized fuel cell gas turbine hybrid system emulator test rig at Thermochemical Power Group (TPG) laboratories of the University of Genoa has been developed to study the fuel cell behavior during different critical operative situations like, for example, load changes (ramp and step), start-up and shut-down and, moreover, to implement an emergency shutdown strategy in order to avoid any damage to the fuel cell and to the whole system: focus has been on cathode/anode differential pressure, which model was validated against experimental data. The real emulator plant (located in Savona University campus) is composed of a 100 kW recuperated micro gas turbine, a modular cathodic vessel (4 modules of 0.8 m3 each) located between recuperator outlet and combustor inlet, and an anodic circuit (1 module of 0.8m3) based on the coupling of a single stage ejector with an anodic vessel. Different simulation tests were carried out to assess the behavior of cathode-anode pressure difference, identifying the best control strategies to minimize the pressure stress on fuel cell stack.
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Zaccaria, Valentina, Zachary Branum et David Tucker. « Fuel Cell Temperature Control With a Pre-Combustor in SOFC Gas Turbine Hybrids During Load Changes ». Dans ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2016 Power Conference and the ASME 2016 10th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fuelcell2016-59278.
Texte intégralRésumé :
The use of high temperature fuel cells, such as Solid Oxide Fuel Cells (SOFCs), for power generation, is considered a very efficient and clean solution to conservation of energy resources. Especially when the SOFC is coupled with a gas turbine, the global system efficiency can go beyond 70% on natural gas LHV. However, the durability of the ceramic material and the system operability can be significantly penalized by thermal stresses due to temperature fluctuations and non-even temperature distributions. Thermal management of the cell during load following is therefore very critical. The purpose of this work was to develop and test a pre-combustor model for real-time applications in hardware-based simulations, and to implement a control strategy in order to keep cathode inlet temperature as constant as possible during different operative conditions of the system. The real-time model of the pre-combustor was incorporated into the existing SOFC model and tested in a hybrid system facility, where a physical gas turbine and hardware components were coupled with a cyber-physical fuel cell for flexible, accurate, and cost-reduced simulations. The control of the fuel flow to the pre-combustor was proven to be very effective in maintaining a constant cathode inlet temperature during a step change in fuel cell load. After imposing a 20 A load variation to the fuel cell, the controller managed to keep the temperature deviation from the nominal value below 0.3% (2 K). Temperature gradients along the cell were maintained below 10 K/cm. An efficiency analysis was performed in order to evaluate the impact of the pre-combustor on the overall system efficiency.
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Kroll, Florian, Annette Nielsen et Stephan Staudacher. « Transient Performance and Control System Design of Solid Oxide Fuel Cell/Gas Turbine Hybrids ». Dans ASME Turbo Expo 2008 : Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50232.
Texte intégralRésumé :
The presentation of a control strategy for the most important SOFC / gas turbine hybrid system maneuvers like start-up, shutdown or system-failures is one of the main issues of this paper. For a successful system simulation during different operational states, a coupled model of a gas turbine and a SOFC was combined with the proposed control system. To keep the model structure lean enough for real-time calculation, a non-linear lumped volume model with modular set up was chosen to achieve an accurate reflection of the dynamic effects. The control strategy takes into account the requirements of the gas turbine components but also necessitates safe operation of the SOFC. Specified boundary conditions are strictly to be considered within the control structure to ensure failure-free and safe operation during the entire operation range. In the presented hybrid cycle a possibility of bypassing both, the cold side of the recuperator and the cathode side of the SOFC is suggested. These two bypasses, which introduce two additional actuators to the system, allow the SOFC stack temperature to be kept in its limits more easily.
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Hao, Xia, Shenghao Wang, Takeaki Sakurai et Katsuhiro Akimoto. « The effect of cathode buffer in small molecule organic solar cells ». Dans 2nd Asia-Pacific Hybrid and Organic Photovoltaics. Valencia : Fundació Scito, 2017. http://dx.doi.org/10.29363/nanoge.ap-hopv.2018.047.
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Chen, Jinwei, Kuanying Gao, Maozong Liang et Huisheng Zhang. « Performance Evaluation of a SOFC-GT Hybrid System With Ejectors for the Anode and Cathode Recirculations ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63745.
Texte intégralRésumé :
The recirculation of the anode and cathode exhaust has huge benefits on the fuel cell system, for instance, keeping proper operating conditions of the reformer and preheating the inlet air which reduces the recuperator size. Furthermore, the ejectors used for the fuel cell recirculation are more reliable and low-cost in maintenance than high temperature blowers. In this paper, an anode and cathode recirculation scheme, both equipped with ejectors, was designed in a Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid system. Additionally, a blower was added between the compressor and the heat exchanger to overcome the significant pressure loss caused by the cathode ejector. This configuration separates the compressor from the fuel cell and turbine components, introducing more flexibility in system modification. The investigations were conducted to analyze the performance of the hybrid system with anode and cathode ejectors in this paper. Firstly, the ejector model was established based on the energy, mass and momentum balance equations. Furthermore, it was validated that the ejector model was consistent with the reference data. Secondly, the stand-alone performance of the anode and cathode ejectors was analyzed. The geometry parameters of the ejectors were determined based on the design conditions. Then the off-design performance was analyzed based on the designed ejectors geometry. The results show that the performance of the ejectors is greatly influenced by the inlet conditions of the primary and secondary fluid mass flow rate. Finally, the anode and cathode ejectors were integrated into the SOFC-GT hybrid system. Meanwhile, the off-design and dynamic behaviors of the whole SOFC-GT hybrid system with anode and cathode ejectors for recirculation loops were analyzed. In the end, the results show that the designed ejectors can effectively satisfy the demands of the SOFC-GT system with anode and cathode recirculation loops. And the safety range of relative fuel flow rate is from 0.42 to 1.22 when the rotator speed is constant.
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Banta, Larry E., Bernardo Restrepo, Alex J. Tsai et David Tucker. « Cathode Temperature Management During Hybrid System Startup ». Dans ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33121.
Texte intégralRésumé :
Management of air flow through the cathode of a hybrid Solid Oxide Fuel Cell/Gas Turbine generation system is of critical importance for the survival of the fragile fuel cell. The cell must be protected from excessive thermal gradients within each cell/stack and from pressure differences between the anode and cathode. While significant modeling of hybrid system performance has been done for the steady state case, only modest attention has been given to startup and shutdown of a hybrid system. Various researchers have performed modeling studies on SOFC during startup, and have concluded that thermal ramp-up times can require anywhere from less than one hour to more than four hours to avoid thermal shock and potential destruction of the fuel cells. For hybrid systems employing single spool turbine/compressor systems, gradual ramping will be difficult because the rotating components must be brought up to full operating speed quickly to avoid stalling the compressor. This paper proposes a strategy for accommodation of the conflicting startup constraints using both experimental data from the NETL HyPer system and simulation approaches.
Rapports d'organisations sur le sujet "Cathodes hybrides"
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Lawson et Thompson. L52100 Hot-Spot Protection for Impressed Current Systems. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), septembre 2003. http://dx.doi.org/10.55274/r0010153.
Texte intégralRésumé :
As pipeline coating and associated cathodic protection (CP) systems age, areas along the pipeline inevitably develop that fall below a prescribed CP criterion. In efforts to meet an adequate CP criterion, engineers often resort to supplementing their existing CP system with magnesium anodes at these "low" potential areas resulting in a "hybrid" cathodic protection system consisting of an impressed current CP system (ICCP) supplemented with magnesium (Mg) anodes. This often achieves the desired result i.e. the potential measured over the pipe becomes more negative. However, there remain several unanswered questions concerning the real benefits to the polarization level of the pipe and the overall effect on the impressed current cathodic protection system. The primary objective of this PRCI project was to develop a better understanding of the relationship between ICCP systems and Mg anodes installed as hot-spot protection. This understanding will assist CP engineers in the design and operation of effective, economic CP systems.