Dissertations / Theses on the topic 'Electrode electrolyte composite'
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Morana, Roberto. "The influence of particle type and process conditions on electrodeposited composite coatings." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/8045.
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Composite materials are usually multi-phase materials, made up from two or more phases, which are combined to provide properties that the individual constituents cannot. This technology represents an economical way to improve product performances avoiding the use of expensive materials. Composite materials can be obtained as films by means of the electrolysis of electroplating solutions in which micrometre- or submicrometre-size particles are suspended: variable amounts of these particles become incorporated in the electrochemically produced solid phase, to which they impart enhanced properties. The main aims of the present work contributing to this thesis are the study of different parameters influencing the electroco-deposition process in order to promote and improve the applicability of such a technology in the high speed electroplating industry. Following a comprehensive review on the electroco-deposition of composite coatings, the phenomena have been analysed moving from a microscopic point of view i. e. the role of the metal ions present in the electrolyte and adsorption on the inert particles and their interactions with the growing metal layer, to a macroscopic point of view i. e. the electrolyte agitation, its influence on particle motion and all the issues related to the presence of particles in an electrolyte during electroplating. In particular the inert particle influence in terms of geometry, dimension and chemical nature (spherical polystyrene particles vs. irregular alumina particles with different dimensions), the metal matrix influence (nickel, copper and zinc), the influence of electrolyte agitation (using a Rotating Cylinder Electrode cell system) and the influence of the coating thickness on particle content in the final coating, using different deposition times, have been examined. The importance of the particle shape has been highlighted showing how incorporating irregular geometries gave higher particle incorporation densities than regular geometries. The influence of the substrate finishing in terms of imperfections has been related to the particle incorporation rate showing how small surface imperfections enhanced the incorporation of particles. Different hydrodynamic regimes have been analysed resulting three different regimes being discerned: laminar, transitional and turbulent. The consequence, in terms of particle incorporation levels, has been found showing how the amount of particles in the coating changed from one regime to another. Different rate-determining steps were related to the hydrodynamics: when the regime is laminar, particles were incorporated as agglomerates and the process was under particle transfer control, whilst in the turbulent zone, the rate determining step was the velocity of reduction of the ions adsorbed on the particle surface.
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Yin, Yijing. "An Experimental Study on PEO Polymer Electrolyte Based All-Solid-State Supercapacitor." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/440.
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Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I2 mediator was added to improve the conductivity of PEO electrolyte and provide pseudocapacitance for all-solid-state supercapacitors. Impedance, cyclic voltammetry, and gavalnostatic charge/discharge measurements were conducted to evaluate the electrochemical performance of PEO polymer electrolytes based all-solid-state supercapacitors. Results demonstrate that the conductivity of PEO electrolyte could be improved to 0.1 S/cm with a mediator concentration of 50wt%. A high conductivity in the PEO electrolyte with mediator is an indication of a high electron exchange rate between the mediator and mediator. The high electron exchange rates at mediator carbon interface and between mediator and mediator are essential in order to obtain a high response rate and high power. This automatically solves the accessibility problem. With the addition of NaI/I2 mediator, the specific capacitance increased more than 30 folds, specific power increased almost 20 folds, and specific energy increased around 10 folds. Further addition of filler to the electrodes along with the mediator could double the specific capacitor and specific power of the all-solid-state supercapacitor. The stability of the corresponded supercapacitor is good within 2000 cycles.
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Bodén, Andreas. "The anode and the electrolyte in the MCFC." Doctoral thesis, KTH, Kemiteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4382.
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A goal of the Swedish government is to increase the usage of renewable fuels and biomass-based fuels. Fuel cells, and especially the MCFC, are useful for these types of fuels. The Swedish market may benefit from the MCFC in two ways: increased efficiency of the biofuels and also utilisation of produced heat in district heating. Most of the commercial MCFC systems today are optimised for use with methane. The possibility to utilise biomass in Sweden makes it important to study how the MCFC may be adapted or optimised for good performance and low degradation with gas produced from biomass or other renewable fuels. This thesis is focused on methods that may be used to investigate and evaluate MCFC electrodes and electrolytes with renewable fuels i.e. CO2-containing gases. The methods and results are both experimental and mathematically modelled. The objectives of this thesis are to better understand how the performance of the anode is dependent on different fuels. Anode kinetics and the water-gas shift reaction have been investigated as well as the possibility to increase cell lifetime by increasing the initial electrolyte amount by having the anode as a reservoir. The effect of segregation of cations in the electrolyte during operation has also been studied. It was found that if the gas composition at the current collector inlet is in equilibrium according to the water gas-shift reaction the gas composition inside the electrode is almost uniform. However, if the gas is not in equilibrium then the concentration gradients inside the current collector have a large effect on the gas composition inside the electrode. The conversion of the gas in the gas flow channels according to the water-gas shift reaction depends on the gas flow rate. For an anode used in a gas mixture of humidified hydrogen and carbon dioxide that are not in equilibrium some solubility of Ni in a (Li/Na)2CO3 mixture was found. To have the anode act as an electrolyte reservoir to prolong cell lifetime the anode pore size should be carefully matched with that of the cathode and a bimodal pore-size distribution for the anode is preferable to have as good performance as possible for as large electrolyte filling degree interval as possible. Modelling results of segregation of cations in the electrolyte during operation indicate that the electrolyte composition changes during operation and that the lithium ions are enriched at the anode for both types of electrolyte used for the MCFC. The electrolyte composition changes are small but might have to be considered in long-time operation. The results from this thesis may be used to better understand how the MCFC may be used for operation with renewable fuels and how electrodes may be designed to prolong cell lifetime.Ett av den svenska regeringens mål är att öka användandet av förnyelsebara bränslen och bränslen från biomassa. Bränsleceller och framförallt MCFC är användbara för dessa typer av bränslen. Den svenska marknaden kan dra fördelar av MCFC på två sätt; ökad bränsleutnyttjandegrad och utnyttjande av producerad värme för fjärrvärme. De flesta kommersiella MCFC-systemen idag är optimerade för användning av metan. Möjligheten att använda biomassa på den svenska marknaden gör det viktigt att studera hur MCFC kan anpassas eller optimeras för bra prestanda och låg degradering för användning med gas från biomassa eller andra förnyelsebara bränslen. Fokus i denna avhandling är på metoder som kan användas för att undersöka och utvärdera MCFC-elektroder och -elektrolyter med förnyelsebara bränslen, dvs. gaser innehållande CO2. Metoderna och resultaten är både experimentella och matematiskt modellerade. Målet med denna avhandling är att bättre förstå hur anodens prestanda beror på användningen av olika bränslen. Anodens kinetik och vattengasskiftreaktionen har studerats liksom möjligheten att förlänga cellens livstid genom att öka den initiala mängden elektrolyt medelst användning av anoden som reservoar. Effekten av segregation av katjoner i elektrolyten under last har också undersökts. Om gassammansättningen är i jämvikt enligt vattengasskiftreaktionen vid inloppet till strömtilledaren kommer gassammansättningen att vara nära uniform inuti elektroden. Om ingående gas inte är i jämvikt kommer stora koncentrationsgradienter uppkomma i strömtilledaren och påverka gassammansättningen i elektroden. Omsättningen med avseende på vattenskiftreaktionen av gasen i flödeskanalen verkar vara beroende av gasens flödeshastighet. För en anod som används i en uppfuktad blandning av vätgas och koldioxid som inte är i jämvikt befanns det att Ni har en viss löslighet i (Li/Na)2CO3. För att kunna använda anoden som reservoar för elektrolyt för att förlänga livstiden för MCFC skall anodens porstorleksfördelning överensstämma med katodens och ha en bimodal porstorleksfördelning för att ge en tillräckligt god prestanda i ett så stort elektrolytfyllnadsgradsintervall som möjligt. Modelleringsresultat för segregering av katjoner i elektrolyten under drift visar att litiumjoner anrikas i anoden för båda typerna av elektrolyt som används i MCFC. Elektrolytkoncentrationsförändringarna är små men kan behövas tas i beaktande vid långa driftstider. Denna avhandlings resultat kan användas för att bättre förstå hur MCFC skall anpassas för drift med förnyelsebara bränslen och hur elektroder kan utformas för att förlänga livstiden.
QC 20100630
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Токарева, Е. С., and E. S. Tokareva. "Получение и функциональные свойства сложнооксидных материалов на основе Ca3Co4O9+δ как перспективных катодов для среднетемпературных ТОТЭ : магистерская диссертация." Master's thesis, б. и, 2021. http://hdl.handle.net/10995/99985.
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Объектами исследования настоящей работы являются катодные материалы на основе сложного оксида Сa3Co4O9+δ. Цель работы – апробация материалов на основе Сa3Co4O9+δ, которые могут быть использованы в качестве катодов для среднетемпературных твердооксидных топливных элементов с протон-проводящими электролитами BaCe0.5Zr0.3Y0.1Yb0.1O3- и BaCe0.7Zr0.1Y0.1Yb0.1O3-. Методом пиролиза цитрат-солевых композиций проведен синтез сложных оксидов Сa3Co4O9+δ, Ca3Co4-xCuxO9 (х = 0.05; 0.1; 0.15; 0.2), BaCe0.5Zr0.3Y0.1Yb0.1O3-δ и BaCe0.7Zr0.1Y0.1Yb0.1O3-. При помощи комплекса современных методов исследования выполнена фазовая, структурная и микроструктурная аттестация оксидов Сa3Co4O9+δ, Ca3Co4 xCuxO9 (х = 0.05; 0.1; 0.15; 0.2), BaCe0.5Zr0.3Y0.1Yb0.1O3-δ и BaCe0.7Zr0.1Y0.1Yb0.1O3-. Термогравиметрическим методом исследована термическая устойчивость Сa3Co4O9+δ на воздухе и в атмосфере аргона. Термическое расширение оксидов Сa3Co4O9+δ и BaCe0.5Zr0.3Y0.1Yb0.1O3-δ изучено методом дилатометрии, доказана их термическая совместимость. Изучена химическая совместимость оксида Сa3Co4O9+δ с электролитными материалами Ba2In1.8W0.2O5.15, 0.7Ba2In2O5·0.3Ba2InNbO6, Ba3Ca1.18Nb1.82O9 δ, BaCe0.5Zr0.3Y0.1Yb0.1O3 δ, а также материалами коллекторных слоев La0.6Sr0.4MnO3-δ и LaNi0.6Fe0.4О3 δ, установлена оптимальная температура припекания катодного материала Сa3Co4O9+δ к электролиту BaCe0.5Zr0.3Y0.1Yb0.1O3-δ. Исследованы температурные зависимости электропроводности Сa3Co4O9+δ и BaCe0.5Zr0.3Y0.1Yb0.1O3-δ на воздухе. Сформированы электроды на основе композитов с различным массовым содержанием Сa3Co4O9+δ и BaCe0.5Zr0.3Y0.1Yb0.1O3-δ на подложках из BaCe0.5Zr0.3Y0.1Yb0.1O3-δ, а также электроды на основе Ca3Co4-xCuxO9 (х = 0; 0.05; 0.1; 0.15) на подложках из BaCe0.7Zr0.1Y0.1Yb0.1O3-δ. Методом импедансной спектроскопии на симметричных ячейках измерены поляризационные характеристики полученных электродов, а также электродов с оксидным коллектором состава La0.6Sr0.4MnO3-δ+2 масс.% CuO.The object of study in this work is a cathode material based on the Сa3Co4O9+δ. The aim of the work is to study the electrochemical behavior of electrodes based on the Сa3Co4O9+δ with the electrolyte materials BaCe0.5Zr0.3Y0.1Yb0.1O3- and BaCe0.7Zr0.1Y0.1Yb0.1O3-. The synthesis of the Сa3Co4O9+δ, Ca3Co4-xCuxO9 (х = 0.05; 0.1; 0.15; 0.2), BaCe0.5Zr0.3Y0.1Yb0.1O3-δ and BaCe0.7Zr0.1Y0.1Yb0.1O3- complex oxides was carried out by pyrolysis of citrate-salt compositions. Using a complex of modern research methods, phase, structural and microstructural attestation of the Сa3Co4O9+δ, Ca3Co4-xCuxO9 (х = 0.05; 0.1; 0.15; 0.2), BaCe0.5Zr0.3Y0.1Yb0.1O3-δ and BaCe0.7Zr0.1Y0.1Yb0.1O3- oxides were carried out. The thermal stability of the Сa3Co4O9+δ in air and in the argon atmosphere was studied by the thermo gravimetrical method. The thermal expansion of the Сa3Co4O9+δ and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ oxides was studied by dilatometry, and their thermal compatibility was proved. The chemical compatibility of the Сa3Co4O9+δ oxide with the electrolyte materials Ba2In1.8W0.2O5.15, 0.7Ba2In2O5·0.3Ba2InNbO6, Ba3Ca1.18Nb1.82O9 δ, BaCe0.5Zr0.3Y0.1Yb0.1O3-δ, Lа0.6Sr0.4MnO3-δ and LaNi0.6Fe0.4О3-δ collector materials was studied, the optimal temperature of the cathode material Сa3Co4O9+δ annealing to the BaCe0.5Zr0.3Y0.1Yb0.1O3-δ electrolyte was established. The temperature dependences of the electrical conductivity of the Сa3Co4O9+δ and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ in air were investigated. Electrodes based on composites with different mass contents of Сa3Co4O9+δ and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ on substrates of BaCe0.5Zr0.3Y0.1Yb0.1O3-δ, as well as electrodes based on Ca3Co4-xCuxO9 (х = 0; 0.05; 0.1; 0.15) on substrates of BaCe0.7Zr0.1Y0.1Yb0.1O3 were formed. The polarization characteristics of the obtained electrodes, including those with an La0.6Sr0.4MnO3-δ+2 wt.% CuO oxide collector, were studied by the method of impedance spectroscopy on the symmetric cells.
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Inaba, Minoru. "Electrochemical Reactions on Polymer Electrolyte Membrane/Electrode Composites." Kyoto University, 1994. http://hdl.handle.net/2433/74664.
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Caldeira, Vincent. "Développement d'électrodes composites architecturées à base de zinc pour accumulateurs alcalins rechargeables." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI065.
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Ces travaux de thèse résultent d’une étude multidisciplinaire dont l’objectif final était d’élaborer une électrode négative à base de zinc pour accumulateur alcalin rechargeable. L’origine de l’étude tient en la découverte surprenante, par la société EASYL, d’un nouveau procédé de synthèse du zincate de calcium (CAZN), matière électrochimiquement active et connue pour ses bonnes caractéristiques de cyclabilité en générateur alcalin rechargeable. L’intérêt de cette découverte réside dans ses caractéristiques avantageuses : la synthèse ultra-rapide se fait en continu, n’utilise aucun système de chauffe ni de solution alcaline et conduit à une granulométrie et une pureté contrôlée du zincate de calcium ; la rendant compatible avec une production industrielle de ce matériau.L’utilisation de CAZN en batterie prismatique de 4 Ah a permis la découverte d’un fonctionnement des électrodes de type cœur-coquille, leur cœur actif étant riche en zinc et leur surface jouant le rôle de couche protectrice ; si la capacité nominale est choisie inférieure à la capacité théorique de la batterie, l’activité à cœur de l’électrode est maintenue sans que sa surface ne soit altérée, ce qui permet d’éviter (ou de ralentir) la formation de dendrite, un effet très bénéfique sur la cyclabilité de l’électrode.Cependant, l’utilisation du zincate de calcium comme seule source de matière active ne semble pas appropriée. En effet, la formation du cœur de zinc conduit à l’apparition d’une couche résistive d’hydroxyde de calcium à sa périphérie, diminuant les performances électrochimiques des électrodes. Aussi surprenant que cela puisse paraitre, il est cependant possible de régénérer une électrode vieillie ayant formé une couche riche en hydroxyde de calcium par un simple repos, soit un arrêt pur et simple de la batterie. La formation de cette couche résistive peut en outre être évitée par l’ajout d’oxyde de zinc sacrificiel au zincate de calcium, additif actif qui s’est avérée efficace tant d’un point de vue morphologique qu’électrochimique.En revanche, la formation contrôlée d’un cœur riche en zinc conduit à la densification du zinc sur lui-même, et diminue la surface de contact matière active/électrolyte et donc les performances électrochimiques. Partant de ce constat, la structure de l’électrode a été intégralement repensée pour permettre la formation, non pas d’un cœur de zinc, mais de plusieurs d’entre eux, par l’emploi de collecteurs de courant multicouches ; cette méthodologie, aussi simple qu’efficace, conduit à d’excellentes performances pratiques et une cyclabilité optimale de la batterieThe work presented in this document results from a multidisciplinary study, the unique goal of which is to develop a negative electrode for alkaline rechargeable batteries. At the origin of this thesis, is the surprising discovery by EASYL of a new way to synthesize calcium zincate (CAZN), an electrochemically active material known for its good cycling characteristics in alkaline batteries. The advantage of such a discovery resides in its unique characteristics: the ultra-fast synthesis is carried out continuously, uses neither heating system nor alkaline solutions, yields pure and tailored CAZN crystals; it is therefore compatible with an industrial production of this material.Its use in a 4 Ah prismatic batteries allowed to unveil a core-shell operation mechanism, in which the electrode evolves towards an active zinc-core surrounded by a protective shell. So, if the nominal capacity remains below the theoretical one, the core of the electrode can be kept active while the surface is maintained, thus avoiding (or at least slowing down) possible dendrite formation and yielding prolonged cycle life.However, the use of calcium zincate as the only active material source is not appropriate, because the formation of the zinc-core leads to the appearance of a resistive layer of calcium hydroxide at its periphery, which reduces the overall electrochemical performance. As surprising as it may seem, it is possible to regenerate an electrode having formed such a calcium hydroxide-rich layer by a simple rest such as a stop of the battery. Nevertheless, it is preferable to avoid the formation of this resistive layer and to do so, the use of a mixture of sacrificial zinc oxide combined with calcium zincate has proven very effective, both from a morphological and an electrochemical point-of-view.However, the controlled formation of a zinc-rich core leads to zinc densification on itself; this decreases the surface of contact between the active material and the electrolyte, and thus the electrochemical performance. This negative effect has been overcome by drastically rethinking the structure of the electrode, in order to allow the formation of multiple and tailored zinc cores. To that goal, multilayers of current collector were employed, which proved simple and effective to reach high-performance and high cyclability zinc electrodes for alkaline batteries
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Anderson, Jordan. "Electrochemical Studies of Nanoscale Composite Materials as Electrodes in Direct Alcohol Fuel Cells." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5104.
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Polymer electrolyte membrane fuel cells (PEMFCs) have recently acquired much attention as alternatives to combustion engines for power conversion. The primary interest in fuel cell technology is the possibility of 60% power conversion efficiency as compared to the 30% maximum theoretical efficiency limited to combustion engines and turbines. Although originally conceived to work with hydrogen as a fuel, difficulties relating to hydrogen storage have prompted much effort in using other fuels. Small organic molecules such as alcohols and formic acid have shown promise as alternatives to hydrogen in PEMFCs due to their higher stability at ambient conditions. The drawbacks for using these fuels in PEMFCs are related to their incomplete oxidation mechanisms, which lead to the production of carbon monoxide (CO). When carbon monoxide is released in fuel cells it binds strongly to the platinum anode thus limiting the adsorption and subsequent oxidation of more fuel. In order to promote the complete oxidation of fuels and limit poisoning due to CO, various metal and metal oxide catalysts have been used. Motivated by promising results seen in fuel cell catalysis, this research project is focused on the design and fabrication of novel platinum-composite catalysts for the electrooxidation of methanol, ethanol and formic acid. Various Pt-composites were fabricated including Pt-Au, Pt-Ru, Pt-Pd and Pt-CeO2 catalysts. Electrochemical techniques were used to determine the catalytic ability of each novel composite toward the electrooxidation of methanol, ethanol and formic acid. This study indicates that the novel composites all have higher catalytic ability than bare Pt electrodes. The increase in catalytic ability is mostly attributed to the increase in CO poison tolerance and promotion of the complete oxidation mechanism of methanol, ethanol and formic acid. Formulations including bi- and tri-composite catalysts were fabricated and in many cases show the highest catalytic oxidation, suggesting tertiary catalytic effects. The combination of bi-metallic composites with ceria also showed highly increased catalytic oxidation ability. The following dissertation expounds on the relationship between composite material and the electrooxidation of methanol, ethanol and formic acid. The full electrochemical and material characterization of each composite electrode is provided.Ph.D.
Doctorate
Chemistry
Sciences
Chemistry
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Tihli, Mustapha. "Relations entre electrosorption et insertion electrochimique dans les carbones : application au stockage d'energie electrique." Reims, 1987. http://www.theses.fr/1987REIMS008.
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Engstrom, Allison Michelle. "Vanadium Oxide Electrochemical Capacitors| An Investigation into Aqueous Capacitive Degradation, Alternate Electrolyte-Solvent Systems, Whole Cell Performance and Graphene Oxide Composite Electrodes." Thesis, University of California, Berkeley, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3616666.
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Vanadium oxide has emerged as a potential electrochemical capacitor material due to its attractive pseudocapacitive performance; however, it is known to suffer from capacitive degradation upon sustained cycling. In this work, the electrochemical cycling behavior of anodically electrodeposited vanadium oxide films with various surface treatments in aqueous solutions is investigated at different pH. Quantitative compositional analysis and morphological studies provide additional insight into the mechanism responsible for capacitive degradation. Furthermore, the capacitance and impedance behavior of vanadium oxide electrochemical capacitor electrodes is compared for both aqueous and nonaqueous electrolyte-solvent systems. Alkali metal chloride and bromide electrolytes were studied in aqueous systems, and nonaqueous systems containing alkali metal bromides were studied in polar aprotic propylene carbonate (PC) or dimethyl sulfoxide (DMSO) solvents. The preferred aqueous and nonaqueous systems identified in the half-cell studies were utilized in symmetric vanadium oxide whole-cells. An aqueous system utilizing a 3.0 M NaCl electrolyte at pH 3.0 exhibited an excellent 96% capacitance retention over 3000 cycles at 10 mV s-1. An equivalent system tested at 500 mV s-1 displayed an increase in capacitance over the first several thousands of cycles, and eventually stabilized over 50,000 cycles. Electrodes cycled in nonaqueous 1.0 M LiBr in PC exhibited mostly non-capacitive charge-storage, and electrodes cycled in LiBr-DMSO exhibited a gradual capacitive decay over 10,000 cycles at 500 mV s-1. Morphological and compositional analyses, as well as electrochemical impedance modeling, provide additional insight into the cause of the cycing behavior. Lastly, reduced graphene oxide and vanadium oxide nanowire composites have been successfully synthesized using electrophoretic deposition for electrochemical capacitor electrodes. The composite material was found to perform with a higher capacitance than electrodes containing only vanadium oxide nanowires by a factor of 4.0 at 10 mV s-1 and 7.5 at 500 mV s-1. The thermally reduced composite material was examined in both symmetric and asymmetric whole cell electrochemical capacitor devices, and although the asymmetric cell achieved both higher energy and power density, the symmetric cell retained a higher capacitance over 50,000 cycles at 200 mV s-1.
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Barchasz, Céline. "Développement d'accumulateurs Li/S." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00681504.
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Ces travaux ont permis d'approfondir les connaissances du mécanisme de déchargepeu conventionnel de l'accumulateur Li/S et de ses limitations. L'ensemble desrésultats a convergé vers une unique conclusion, à savoir que le système Li/S estprincipalement limité par le phénomène de passivation de l'électrode positive en finde décharge. Les polysulfures de lithium à chaines courtes précipitent à la surface del'électrode positive de soufre. Isolants électroniques, ils sont responsables de la perteprogressive de surface active de l'électrode et de la fin prématurée de la décharge.Ainsi, les performances électrochimiques ont pu être significativement améliorées entravaillant sur la morphologie de l'électrode positive, et sur la composition del'électrolyte. En augmentant la surface spécifique de l'électrode, la quantité depolysulfures de lithium qui peut précipiter en fin de décharge est augmentée, et lapassivation totale de l'électrode est retardée. En augmentant la solubilité despolysulfures de lithium dans l'électrolyte, la précipitation des espèces est retardée etla décharge prolongée. Dans cette optique, les solvants de type PEGDME semblentêtre les plus prometteurs à ce jour. Enfin, un mécanisme possible de réduction dusoufre en électrolyte de type éther a pu être proposé.
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Subbaraman, Ramachandran. "A multi-scale hierarchical approach for understanding the structure of the polymer electrolyte membrane fuel cell (PEMFC) electrodes - from nanoparticales to composites." online version, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=case1205852564.
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Subbaraman, Ramachandran. "A MULTI-SCALE HIERARCHICAL APPROACH FOR UNDERSTANDING THE STRUCTURE OF THE POLYMER ELECTROLYTE MEMBRANE FUEL CELL (PEMFC) ELECTRODES - FROM NANOPARTICLES TO COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1205852564.
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Boulenouar-Mohamedi, Fatma Zohra. "Étude de l'oxydation anodique de l'hydrogène à l'interface métal/zircone stabilisée à haute température (métal=platine, nickel, cuivre)." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0055.
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Ce travail s'inscrit dans le cadre de recherches conduites sur les piles a combustible fonctionnant a haute temperature et mettant en jeu un electrolyte solide conducteur par ions oxydes (zircone stabilisee a l'oxyde d'yttrium: ysz). L'objet de cette recherche est de preciser les influences respectives des pressions partielles d'hydrogene et d'eau dans la polarisation anodique de l'interface metal/ysz, le metal etant: le platine, le nickel ou le cuivre. A l'equilibre, l'etude a montre l'interet de differencier les roles respectifs de l'hydrogene et de la vapeur d'eau et de ne pas traiter les resultats uniquement en terme de pression partielle d'oxygene. Des circuits equivalents rendant compte des reponses de l'electrode sont proposes. Par ailleurs, les resultats obtenus sous polarisation ont montre l'effet electrocatalytique de la vapeur d'eau sur la reaction d'oxydation anodique de l'hydrogene
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CAPRONI, ERICA. "Eletrolitos sólidos cerâmicos a base de óxido de zircônio para a detecção de oxigênio." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11534.
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Made available in DSpace on 2014-10-09T12:52:58Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:59:04Z (GMT). No. of bitstreams: 0
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:03/07331-0
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Géniès, Sylvie. "Étude de la passivation de l'électrode carbone-lithium." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0008.
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Le phenomene de la passivation de l'electrode carbone-lithium utilisee comme pole negatif dans la batterie lithium-ion est d'une importance cruciale dans les caracteristiques du fonctionnement de cette electrode. Il en fixe la capacite reversible (ou utile), la duree de vie et le taux d'autodecharge. Ce travail est une contribution a la comprehension des processus chimiques et electrochimiques survenant a la surface de l'electrode au cours de l'echange du lithium avec une solution electrolytique a base d'un ou plusieurs solvant(s) organique(s) et d'un sel de lithium et conduisant a la formation d'un film de passivation. Apres une presentation bibliographique qui situe l'etude dans son contexte national et international, le travail experimental s'adresse dans un premier temps au role des parametres qui influent sur le processus de passivation tels que la nature de l'anion du sel de lithium et celle du materiau carbone ainsi que la composition de l'electrolyte. La caracterisation de ce film obtenu par des methodes chimiques ou electrochimiques utilise une large gamme de techniques : drx, meb, met, microscopie a champ proche (afm), ir-tf, rmn, esca, atg et dsc. Les techniques electrochimiques sont aussi variees : chronoamperometrie, chronopotentiometrie, impedance complexe et voltamperometrie cyclique. Les resultats obtenus sont pour la plupart originaux. Ainsi, les analyses de la composition chimique du film par esca et par ir-tf sont non seulement completes et nouvelles mais mettent en evidence pour la premiere fois le caractere polymere du film. Ce resultat devrait avoir des repercutions importantes sur l'elaboration ex situ du film pour une etude plus approfondie. L'observation du film forme sur un graphite hautement oriente par afm a permis d'obtenir les images les plus precises et les plus claires jamais publiees. L'etude electrochimique est completee par une synthese chimique du film par une methode originale. L'utilisation de ce film comme electrolyte de type plastifie a ete demontree.
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Woo, Sahng Hyuck. "Membranes composites acide perfluorosulfonique (PFSA)/argile pour un fonctionnement à faible humidité relative et haute température des piles à combustible à membrane échangeuse de protons (PEMFC)." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM033.
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Cette thèse introduit de nouvelles membranes électrolytiques pouvant fonctionner à faible humidité relative (inférieure à 50%) et à une température intermédiaire, c'est-à-dire 90°C voire au-delà. Plus spécifiquement, la thèse tire profit de l'hygroscopicité de la morphologie d’argiles naturelles, lasépiolite microfibreuse et l’halloysite tubulaire . Ces nanoargiles ont été intégrées à des suspensions de Nafion® ou Aquivion pour préparer des membranes composites. Elles ont été fonctionnalisées et prétraitées pour les rendre conductrices protoniques et améliorer leur compatibilité avec les matrices perfluorosulfoniques utilisés. Ces argiles ont d’abord été caractérisées avant leur incorporation dans la matrice polymère : ATR-FTIR (spectroscopie infrarouge à transformée de Fourier totale atténuée), Py-GC/MS (spectrométrie de masse par chromatographie en phase gazeuse à pyrolyse) et ATG (analyse thermogravimétrique). Les propriétés des nanoargiles prétraitées ont enfin été caractérisées par XRD (diffraction des rayons X) et EDS. Les membranes composites préparées ont ensuite été caractérisées pour la conductivité protonique, l'absorption d'eau, le gonflement, la résistance thermomécanique et la stabilité chimique. L'état de dispersion des argiles à l'intérieur de la phase de polymère a été observé par SEM/EDS (microscopie électronique à balayage à émission de champ / spectroscopie à rayons X à dispersion d'énergie). La stabilité chimique vis-à-vis de l'attaque radicale contre les membranes composites a été étudiée par mesure de la formation d’ions fluorure (F-). La conductivité protonique des membranes composites a également été calculée à partir des résistances mesurées dans dans une large gamme d'humidités relatives et de températures. Des mesures thermomécaniques par analyse mécanique dynamique ont montré que la morphologie allongée particulière des argiles choisies participe à l'amélioration des propriétés mécaniques des membranes composites tout en réduisant le taux de gonflement. Les performances en assemblage membrane électrodes ont été évaluées pour mettre en évidence l’avantage de la présence de ces nanoargiles dans les membranes composites en ce qui concerne l’humidité relative du gaz d’alimentation, la température de fonctionnement de la cellule et la perméation à l’hydrogène. Des résumés détaillés comprenant les principaux résultats ont été fournis au début de chaque chapitreThis thesis introduces novel electrolyte membranes which can be operated at low relative humidity (below 50%) and intermediate temperature, i.e., 90℃. More specifically, the thesis takes benefit from hygroscopicity of microfibrous SEP (sepiolite) and tubular HNT (halloysite). Changes in Nafion membrane properties with blending time were studied. Moreover, these nanoclays are functionalized and pretreated to make them proton conductive and to improve their compatibility with short-side-chain PFSA (perfluorosulfonic acid) composite membranes based on Aquivion. To begin with, functionalized and pretreated clay nanoparticles are characterized prior to incorporation in polymer matrix: ATR-FTIR (attenuated total reflection-fourier transform infrared spectroscopy), Py-GC/MS (pyrolysis gas chromatography mass spectrometry), and TGA (thermogravimetric analysis). Composites membranes have them been prepared and characterized for proton conductivity, water uptake, swelling, thermo-mechanical strength and chemical stability. The dispersion state of SEP and HNT inside polymer phase was observed using SEM/EDS (field emission scanning electron microscopy/Energy dispersive X-ray spectroscopy). The properties of pretreated nanoclays are characterized using XRD (X-ray diffraction) and EDS. Chemical stability regarding radical attack against composite membranes is clarified using Ion meter through fluoride ion (F-) analysis. Proton conductivity of composite membranes is also measured under condition of different relative humidity and temperature. Following this, it is demonstrated by DMA (dynamic mechanical analysis) results that the particular elongated morphology of SEPs and HNTs participates to improving mechanical property of the composite membranes with decreased swelling ratio. MEAs (membrane electrode assembly) performance are evaluated to understand the advantage of the presence of nanoclays in the composite membranes regarding the relative humidity of the feeding gas, the operating temperature of the cell, and the hydrogen crossover. Detailed abstracts including main results were provided at the beginning of each chapter
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Adami, Fatos. "Analyse infra-rouge in-situ de l'interface electrode metallique/solution par la methode mirftirs : mise au point et application de la technique a l'etude de l'electropolymerisation des phenols sur electrode de fer." Paris 7, 1987. http://www.theses.fr/1987PA077042.
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Caproni, Érica. "Estudo de eletrólitos sólidos cerâmicos à base de óxido de zircônio para a detecção de oxigênio." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-30032012-101612/.
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Tendo como vantagem a elevada resistência ao choque térmico da zircônia:magnésia e a alta condutividade iônica da zircônia:ítria, compósitos dessas cerâmicas foram preparados por meio da mistura, em diferentes concentrações, de eletrólitos sólidos de ZrO2: 8,6 mol% MgO e de ZrO2: 3 mol% Y2O3, compactação e sinterização. A caracterização microestrutural foi feita por meio de difração de raios X e microscopia eletrônica de varredura. A análise do comportamento térmico foi feita por dilatometria. As propriedades elétricas foram estudadas por meio de espectroscopia de impedância. Foi feita uma montagem experimental para monitorar a resposta elétrica gerada em função do teor de oxigênio a altas temperaturas. Os principais resultados mostram que os compósitos cerâmicos são parcialmente estabilizados nas fases monoclínica, cúbica e tetragonal, e apresentam comportamento térmico similar ao apresentado por eletrólitos sólidos de zircônia:magnésia de dispositivos sensores de oxigênio. Além disso, os resultados de análise de espectroscopia de impedância mostram que a adição da zircônia:ítria melhora o comportamento elétrico da zircônia:magnésia, e que resposta elétrica gerada é dependente do teor de oxigênio a 1000 °C, mostrando ser possível construir sensores de oxigênio utilizando compósitos cerâmicos.Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO2: 8.6 mol% MgO and ZrO2: 3mol% Y2O3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO2: 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 °C, showing that the ceramic composites can be used in oxygen sensors.
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Fichou, Denis. "L'interface oxyde de zinc/électrolyte : étude des processus primaires." Paris 6, 1986. http://www.theses.fr/1986PA066259.
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Sar, Jaroslaw. "Interfaces et durabilité d'électrodes avancées pour l'énergie : IT-SOFC et SOEC Coral Microstructure of Graded CGO/LSCF Oxygen Electrode by Electrostatic Spray Deposition for Energy (IT-SOFC, SOEC) Electrochemical properties of graded and homogeneous Ce0.9Gd0.1O2-δ-La0.6Sr0.4Co0.2Fe0.8O3-δ composite electrodes for intermediate-temperature solid oxide fuel cells Three dimensional analysis of Ce0.9Gd0.1O1.95–La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen electrode for solid oxide cells Mechanical behavior of Ce0.9Gd0.1O1.95-La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen electrode with a coral microstructure for solid oxide fuel cell and solid oxide electrolyzer cell Durability test on coral Ce0.9Gd0.1O2-δ-La0.6Sr0.4Co0.2Fe0.8O3-δ with La0.6Sr0.4Co0.2Fe0.8O3-δ current collector working in SOFC and SOEC modes." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI106.
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Interfaces et durabilité des électrodes de pointe pour l'énergie (PAC et EHT)L'objectif de cette thèse concerne l'élaboration, par atomisation électrostatique, d'une électrode à oxygène à architecture innovante, basée sur un composite Ce0.9Gd0.1O1.95 (CGO) - La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) possédant un gradient de composition ou une composition homogène. Cette électrode a été déposée sur un substrat de zircone yttriée (YSZ = 8 % mol. Y2O3-ZrO2) sur laquelle, a été intercalée au préalable une couche barrière mince et dense de CGO. Cette électrode possède une microstructure innovante, à porosité élevée permettant d'obtenir une grande surface active qui devrait conduire à l'amélioration des performances électrochimiques. Le comportement électrique de l'électrode a été étudié par spectroscopie d'impédance en fonction de la température et sous air. Une description microstructurale détaillée a été effectuée à l'aide d'un modèle de reconstruction 3D obtenu par -MEB équipé d'une sonde ionique focalisée et par nanotomographie X. Ces propriétés microstructurales ont été reliées aux propriétés électriques. Les propriétés mécaniques et tribologiques de cette électrode composite ont été déterminées par des tests du scotch et ultra-microindentation. Finalement, des tests de durabilité ont été effectués sur une électrode de grande taille possédant une surface active de 45 cm2 jusqu'à 800 h à environ 770°C, dans une cellule complète de configurations PAC et fonctionnant respectivement sous H2 et un mélange H2/H2OInterfaces and durability of advanced electrodes for energy (IT-SOFC and SOEC)The objective of this PhD thesis is to fabricate advanced oxygen electrode based on Ce0.9Gd0.1O1.95 (CGO) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) with graded and homogeneous composition onto yttria-stabilized zirconia (YSZ = 8 mol. % Y2O3-doped ZrO2) electrolyte using electrostatic spray deposition. A thin and dense layer of CGO was inserted between LSCF and YSZ to serve as a barrier diffusion layer. The novel microstructure with high porosity and large surface area is expected to improve the electrochemical performances. The electrical behavior of the electrode was investigated by impedance spectroscopy versus temperature in air. A detailed microstructural description was performed by 3D reconstructed model from FIB-SEM and X-ray nanotomography and related to electrical properties. The mechanical analysis was performed by scratch and ultramicroindentation tests. Finally, durability tests were performed on the electrode with 45 cm2 oxygen active area, up to 800 h at around 770°C, in full cell SOFC and SOEC configurations operating respectively in H2 and H2/ H2O mixture
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Malki, Abdelhafid. "Transformation électrocatalytique de produits issus de la biomasse : oxydation du fructose sur électrodes d'or et de platine." Poitiers, 1988. http://www.theses.fr/1988POIT2274.
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L'oxydation electrochimique du fructose en milieu basique et en milieu acide est realisee: une etude cinetique est effectuee, on etudie la modification des proprietes catalytiques superficielles des electrodes par adjonction d'adatomes, on fait plusieurs electrolyses a potentiel programme montrant que l'on obtient par cette reaction un melange d'acides gluconique, tartrique et citrique
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Forano, Claude. "Les conducteurs protoniques : HSbO3.nH2O ET SnO2.nH2O : caracterisation, etude rmn et applications." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21069.
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Preparation par une methode sol-gel permettant d'obtenir des materiaux de grande purete; mise en evidence de differences structurales importantes, d'une tres grande homogeneite morphologique et d'une difference importante de la taille des cristallites. Confirmation par rmn de l'existence de plusieurs especes protonees. Etude des variations de la conductivite en fonction de la temperature; influence de la teneur en eau. Mise en evidence de la relation entre la conductivite electrique et la mobilite protonique a partir de mesures des temps de relaxation et proposition d'un mecanisme de type grotthus. Elaboration de couches epaisses par serigraphie; possibilites d'application dans des dispositifs microioniques. Essais d'utilisation pour la detection de h::(2)
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WENG, HU-CHENG, and 翁瑚珹. "Supercapacitance of Polyaniline/Mesoporous Carbon Composite Electrode in C6H4(OH)2/H2SO4 Electrolyte." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6jn5hk.
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碩士國立勤益科技大學
化工與材料工程系
107
In this study, carbon mesoporous material, CMK-3, was adopted as supporting material for electroactive polymerspolyaniline (PANI), polyaniline, for supercapacitor application. Where hydroquinone (HQ) was also integrated to enhance the redox reaction of PANI. The results show that the addition of PANI improves the capacitance of electrode from 101 F/g (CMK-3) to 480 F/g (PANI/CMK-3), the addition of HQ furtherly improves the capacitance to 684 F/g (PANI/CMK-3/HQ). In-situ analyses including cyclic voltammetry (CV), chronopotentiometry (CP), electron impedance spectrum (EIS) analyses were applied for electrode performance examination. For materials characterization, the crystal structure, morphology, microstructure, and porosity were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), and 77K N2 adsorption/desorption analyses, respectively. The effects of PANI polymerization time, HQ concentration, and PANI/CMK-3 ratio on capacitance were discussed. The research results of this thesis can be summarized as follows:(i)The PANI provides higher energy density and also acts as binder of the electrode；(ii) The CMK-3 provides higher electron double layer capacitance EDLC and stabilize the polyaniline by its highly porosity；(iii)With the addition of HQ, the capacitance of PANI/CMK-3 was further enhanced.The durability was also studied by long-term operation test. The results show that PANI/CMK-3/HQ with great potential for supercapacitor application. Finally, the potential of PANI/CMK-3/HQ based supercapacitor was successfully demonstrated.
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Wen, Chih-yu, and 溫治宇. "Study of supercapacitor fabricated with composite electrodes and gel polymer electrolyte." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nc72b5.
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博士國立中山大學
電機工程學系研究所
106
This study separately mixed Ni(CH3COO)2 and H2O4W solutions with mesocarbon microbeads (MCMBs), filtered the resulting solution, and then subjected the carbon paste to heat treatments to give rise to composite carbon powder. The powder was then mixed with an adhesive and then applied to a conductive carbon (CC)/ITO glass substrate, which completed the fabrication of a composite electrode for supercapacitors. Gel polymer electrolytes (GPEs) were made using lithium salts LiClO4 and LiBOB in propylene carbonate (PC) solvent. The resulting electrolytes were tested using AC impedance spectroscopy and galvanostatic charge-discharge efficiency tests to determine the influence of the lithium salt used on the capacitance properties of the GPE. Finally, charge-discharge efficiency tests, ambient temperature tests, and lifetime tests were conducted on the supercapacitor. The results show that a 0.75-M H2O4W solution paired with a 100C heat treatment to produce a composite-structured carbon powder in addition to 25 wt.% carbon black and 2 wt.% adhesive results in a composite electrode with the best capacitance properties. Its specific capacitance in a electrolyte (1 M LiClO4) was 249 F∙g-1. The GPE (Sample 4) made with 8 wt.% LiClO4 and 30 wt.% Ionic liquid (IL) presented lower bulk impedance, lower electrolyte-electrode interface impedance, a lower device decline rate, and a higher specific capacitance. The charge-discharge tests revealed that within the voltage range of 0 V to 2.5 V and a charge/discharge current density of 0.3 A∙g-1, the WO3/MCMB presented the optimal specific capacitance of 234.22 F∙g-1. From this results, It could be calculated that the energy density was 293 Wh∙kg-1, and the power density was 105.4 kW∙kg-1 (discharge current @0.03 A). The results therefore demonstrate that the composite electrode fabricated in this study exist good performance capacitance. Furthermore, the composite electrode presented near-100% charge-discharge efficiency and good adhesion between the electrode materials and the substrate after 1,000 charge-discharge cycles in the galvanostatic charge-discharge efficiency tests and service-life tests.
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CAO, MENG SIAN, and 曹孟賢. "The study of electrolyte for GNS/CNT composites applied to supercapcaitor electrode." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/71031097506603495008.
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碩士國立雲林科技大學
化學工程與材料工程系
103
Supercapacitor is a high efficiency energy storage element, the performance is between traditional capacitor and chemical capacitor. Electrode material and electrolyte is the factor influence performance. Electrode materials mainly include carbon materials, metal oxides and conductive polymer material. Carbon material is widely used due to electrochemical stability and low prices. Graphene and carbon nanotubes both contain good conductive, and KOH is the neutral alkalinity electrolyte that largely applied in supercapacitor. Therefore in this report, we choose LiPF6/EC/DMC organic electrolyte to compare the electrochemical performance of electrode. We use scanning electron microscope(SEM), Cyclic voltammetry (CV), AC impedance（EIS） to analysis characterization and test . The results indicate the capacity and the energy density of KOH solution electrolyte and LiPF6/EC/DMC organic electrolyte at cooling rate condition 110℃/min are 110.3 F/g、15.32 wh/kg and 48.32F/g、101.225wh/kg respectively. The best parameters of oxygen plasma is 100W and 45 minute. The capacity of two capacity is 181.32 F/g and 80.98F/g respectively, its increase 64.38% (KOH) and 69.35% (LiPF6/EC/DMC)
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Huang, Kuan-Chieh, and 黃冠傑. "On the Composite Counter Electrodes and Quasi-Solid-State Electrolytes for Dye-Sensitized Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/29598026080233046186.
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博士國立臺灣大學
化學工程學研究所
100
The exploration of solar energy is one of most intensive studies on the technologies of green energy in recent years. A new generation of solar cell, dye-sensitized solar cell (DSSC), has been investigated worldwide due to the advantages, including facile development of cell, flexibility, and colorful appearance. In terms of (1) improving the power-conversion efficiency (η) of cell (Chapter 3), (2) reducing the consumption of fabrication of cell (Chapter 4 and Chapter 5), and (3) enhancing the long-term durability of cell (Chapter 6 and Chapter 7), various nanomaterials have been synthesized and prepared for the counter electrodes (CEs) and the electrolytes of the DSSCs in this dissertation. For improving the η of DSSC, a conducting glass substrate spin-coated with a composite thin film, consisting of platinum nanoparticles (PtNPs) and multi-wall carbon nanotubes (MWCNTs), is prepared for a CE of a DSSC (Chapter 3). A homemade polymer, poly(oxyethylene)-segmented imide (POEM), is used and served as stabilizer and dispersant for MWCNTs in the aqueous solution. The best electro-catalytic ability of the film for the reduction of tri-iodide (I3-) ions is obtained after the film is annealed at 390 oC. This is attributed to the complete decomposition of non-conducting POEM, to the formation of PtNP with a moderate crystalline size, and to the surface roughness of film. Thus, an η of 8.47 ± 0.21% of the DSSC with the CE based on the composite film shows much higher than that of a DSSC applying a Pt-coated CE (η = 7.41 ± 0.24%) under illumination of 100 mW cm-2. For reducing the consumption of fabrication of DSSC, an electro-polymerized composite thin film consisting of nanographites (NGs) and polyaniline (PANI) on the conducting glass substrate is prepared for the replacement of costly Pt as the CE of a DSSC (Chapter 4). A well dispersing ability of NG/aniline particles in the depositing solution is obtained after the particles are treated by reflux-condensation; thereby improving the depositing quality of NG/PANI composite film on the substrate by electro-polymerization. The fine distribution of NGs in the film results in an enhanced conductivity of it, with reference to the conductivity of pristine PANI film. Thus, a percentage of 98.3%, corresponding to the η of a DSSC made of Pt-coated CE, for the DSSC with the NG/PANI CE is acquired. The competitive electro-catalytic ability of the film in comparison to that of film of Pt is confirmed by scanning electrochemical microscopy. In addition, hollow spherical PANI (hsPANI) particles are also deposited on the conducting glass substrate by means of reflux-condensation and electro-polymerization for the CE of a DSSC (Chapter 5). A larger active surface area (A) of thin film consisting of hsPANI particles is estimated to be 0.191 cm2, with reference to that of pristine PANI film (A = 0.126 cm2) by rotating disk electrode. The increased A is beneficial for the reduction of I3-. Thus, a percentage of 95.4%, corresponding to the η of a DSSC with a Pt-coated CE, for the DSSC made of hsPANI CE is obtained. The film consisting of hsPANI particles can serve as a potential alternative for the replacement of Pt catalyst on the CE. For enhancing the long-term durability of DSSC, a liquid electrolyte based on organic solvent is converted into a quasi-solid-state electrolyte by the gelation using a polymer, poly(vinyidene fluoride-co-hexafluoro propylene) (PVDF-HFP), for a DSSC (Chapter 6). The crystallinity of PVDF-HFP decreases when high thermal stable nanoparticles of aluminum nitride (AlN) are incorporated in the quasi-solid-state electrolyte. Thus, the diffusion coefficient of iodide (I-) is increased from 2.97 × 10-6 to 3.52 × 10-6 cm2 s-1. Under 1 sun illumination, the η of a DSSC with this quasi-solid-state electrolyte gives a higher value of 5.27 ± 0.23%, compared to that of a DSSC without adding AlN in its electrolyte (η = 4.75 ± 0.08%). Merely a loss of 5% in η of the DSSC with reference to its initial η is observed for the at-rest durability of the quasi-solid-state DSSC in a period of 1,000 h. In addition, a solvent-free ionic liquid (IL)-based electrolyte containing a synthesized composite of MWCNT/crown ether is prepared for a quasi-solid-state DSSC (Chapter 7). An IL, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4), is used. Prior to the characterization of performance for the DSSC with this IL electrolyte, crown ether, 15-crown-5, is preferably chosen owning to its appropriate size of cavity for capturing the lithium (Li+) in the electrolyte in comparison to the capturing abilities of 12-crown-4 and 18-crown-6. Thus, the decrease in electrostatic force between Li+ and I- leads to an improvement of the exchange reaction of I- and I3- by adding the MWCNT/15-crown-5 composite in the EMIBF4 electrolyte. The transport of electrons is facilitated by MWCNTs. Consequently, the values of short-circuit current density and η of the DSSC with both MWCNT/15-crown-5 and EMIBF4 in its electrolyte exhibits increases by 71.2 and 38.8%, respectively, with reference to these values of a DSSC with a bare EMIBF4. The at-rest durability of this quasi-solid-state DSSC is found to be unfailing for a period of 1,200 h.
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Huang, Yao-Ting, and 黃耀霆. "Preparation of Embedded Multifunctional Energy Storage Composites with Activated Carbon Fiber Electrode and PVdF-based Gel Polymer Electrolytes ¬— on Electrochemical and Mechanical Properties." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/2efhp8.
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碩士國立臺灣大學
工程科學及海洋工程學研究所
107
This study demonstrates a standardized process to fabricate embedded multifunctional energy storage composites. Using Activated carbon fiber electrodes and PVdF-based gel electrolyte as building materials for supercapacitors. Two-step packaging method is used to fabricate glass-fiber reinforced polymer (GFRP) composites that can make it simultaneously bear mechanical loadings and store energy. Carbon fabric with three different activation methods and PVdF-based gel electrolyte are characterized by an electrochemical test. In addition, the electrochemical properties of the multifunctional energy storage composites are determined by galvanostatic charge-discharge (GCD), cyclic voltammetry and AC impedance method (EIS). The result shows that specific capacitance and energy density of supercapacitor with GFRP have 142 mF/g and 15.7 Wkg^(-1) provide 20% and 30% enhancement performance than a bare cell, respectively. The mechanical properties of the supercapacitor embedding of GFRP are investigated by tensile test; the result shows the average stress of 350.1 MPa and Young’s modulus of 14 GPa. Furthermore, to understand the electrical properties of multifunctional energy storage composites with external load changes, two different situations were also established. With the tensile load increase, the supercapacitor energy density is increased by around 10%, and the structural supercapacitor undergoing cyclic tensile is still functioning normally before the GFRP failure load.