Depuis une dizaine d'années, on observe un développement de l'électronique embarquée intégrée à la plupart des objets que nous utilisons au quotidien. Il s'agit maintenant de les interconnecter en créant des réseaux embarqués connectés tels que les réseaux de capteurs autonomes sans fils. La miniaturisation des composants permet d'envisager une autonomie énergétique de ces réseaux composés de capteurs, récupérateurs d'énergie et de micro-batteries. Cependant la faible durée de vie des batteries et leur puissance limitée sont problématiques pour de telles applications. Les micro-supercondensateurs représentent une alternative pertinente pour la gestion de l'énergie dans les systèmes embarqués, notamment grâce à leur durée de vie très élevée. L'objectif de cette thèse concerne l'optimisation des performances de ces dispositifs en termes de densité de puissance et d'énergie. La capacité du supercondensateur étant proportionnelle à la surface électrochimiquement active des électrodes, nous nous sommes donc intéressés à la structuration de collecteurs de courant en or pour optimiser les performances des micro-supercondensateurs à base d'oxyde de ruthénium. Nous avons sélectionné deux principales techniques pour fabriquer une structure tridimensionnelle de l'or. Dans un premier temps, le dépôt physique d'or par évaporation à angle oblique (OAD) nous a permis de réaliser un substrat colonnaire suivi d'un dépôt d'oxyde de ruthénium. Dans un deuxième temps, nous avons mis en place un dépôt électrochimique d'or avec un modèle dynamique à bulles d'hydrogène. Cette technique permet la fabrication d'une structure d'or en trois dimensions par le biais d'un dépôt d'or réalisé simultanément avec une évolution d'hydrogène. L'électrodéposition de l'oxyde de ruthénium sur cette structure poreuse a montré une très bonne compatibilité notamment en terme d'homogénéité du dépôt, une forte capacité à faible vitesse de balayage (> 3 F/cm2) et une bonne cyclabilité. Pour tester les performances de ces électrodes, nous avons réalisé un dispositif complet en configuration empilée présentant de bonnes caractéristiques. Cette technologie de fabrication a pu par ailleurs être transférée à la micro-échelle pour des dispositifs planaires à l'aide de procédés de photolithographie sur électrodes interdigitées. / The increasing importance of portable and wearable electronics as well as embedded wireless sensor networks has made energy autonomy a critical issue. Micro-energy autonomy solutions based on the combination of energy harvesting and storage may play a decisive role. However, the short lifetime of micro-batteries is problematic. Micro-supercapacitors are a promising solution in terms of energy storage for embedded systems on the account of their important lifetime. In this work we have focused on the optimization of the performances of micro-supercapacitors in terms of energy and power density. As the capacitance is directly related to the accessible surface area of the electrodes, we have investigated the structuration of the current collectors in order to improve the performances of ruthenium oxide-based micro-supercapacitors. Two mains technics have been studied to obtain three dimensional structures. In a first phase, the oblique angle physical vapor deposition (OAD) has been investigated to fabricate a columnar gold structure, subsequently covered by an electrochemical ruthenium oxide. In a second phase, a highly porous gold architecture has been studied using electrodeposition via a hydrogen bubbles dynamic template. The ruthenium oxide electrodeposited on the resulting mesoporous gold structure shows good compatibility, in terms of homogeneous deposition, with a significant capacitance at slow rate (> 3F.cm-2) and an important cyclability. As proof of concept, a device has been designed in a stack configuration with good performances. Moreover, the technology finalized for electrodes fabrication has been transferred to the micro-scale on planar interdigitated devices using a suitable photolithography process.

This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.

This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.

Les travaux présentés dans cette thèse concernent la modélisation, le dimensionnement et la commande d'un coffre composé de supercondensateurs et d'un convertisseur DC/DC permettant d’alimenter les auxiliaires d’un trolleybus ou les moteurs de traction lors des coupures de la ligne aérienne. Dans la première partie, nous nous sommes intéressés au dimensionnement du système destockage pour une application du type récupération de l'énergie au freinage d'un trolleybus. Les modèles directes et inverses de la chaine cinématique ont été étudiés afin de définir une stratégie de dimensionnement du coffre s'appuyant sur le plan de Ragon. La seconde partie aborde la problématique de la fiabilité de l'élément de stockage. Le but est d'évaluer les contraintes que subissent les supercondensateurs en cours de fonctionnement et de prédire le vieillissement de ces derniers. Pour ce faire, nous avons développé et validé un modèle électrothermique du coffre de supercondensateurs. Ce modèle électrothermique a également été couplé à des lois de vieillissement permettant ainsi de prendre en compte les variations paramétriques majeures de ce système. Les résultats de ce couplage montrent l'impact de la dispersion des températures à l'intérieur du coffre sur la durée de vie de chaquesupercondensateur et du système de stockage. Finalement, le contrôle du convertisseur statique (hacheur Buck/Boost) associé auxsupercondensateurs est abordé. Une étude théorique a été menée pour synthétiser des lois de commande par mode de glissement et par PI appliqués au mode élévateur du hacheur (Boost). Ces lois de commande ont été validées sur un banc de test constitué d'un hacheur réversible, d'une alimentation DC, d'une charge résistive et de huit supercondensateurs. La comparaisondes résultats expérimentaux mettre en évidence l'intérêt de la commande par mode glissant enraison de sa robustesse et de sa réactivité par rapport à une commande classique (PI). / The studies presented in this thesis concern the thermal modeling, sizing and control of a stack composed of supercapacitors and DC/DC converter that feeds the auxiliaries or traction motors of the trolleybus in the case of electrical microcuts. In the first part, we were interested in the sizing of the storage system for an application concerning the recovering braking energy of a trolleybus. Direct and inverse models of the kinematic chain were studied in order to define a design strategy based on the Ragon. The second part concerns the reliability of the storage system. The aim is to evaluate the stresses on supercapacitors during cycling and to predict the aging of the components. Toachieve this goal, we have developed and validated an electrothermal model of the stack. This model was then coupled to aging laws allowing taking into account the major parametric variation of the system. The results show the impact of the dispersion of temperatures inside the stack on the life time of each supercapacitors in the storage system. Finally, the control of the static converter (Buck/Boost converter) combined with supercapacitors is analyzed. A theoretical study was conducted to synthesize PI and sliding mode controller applied to a boost converter. This control laws has been validated on a test bench consisting of a reversible converter, a DC power supply, a resistive load and eight supercapacitors. The experimental results show the advantage of sliding mode control in terms of robustness and reactivity compared to a classical PI control.

Room temperature molten liquids are proposed to be good alternates for volatile and harmful organic compounds. They are useful in varied areas of applications ranging from synthesis, catalysis to energy storage molten electrolytes have certain unique characteristics such as low vapour pressure, reasonably high ionic conductivity, high thermal stability and wide electrochemical window. These molten liquids can be classified in to two types depending on the nature of the species present in the liquids. One, those liquids consists only of ions (e.g) conventional imidazolium based ionic liquids and other that consists of ions and solvents (e g) acetamide eutectics. Acetamide and its eutectics from room temperature molten solvents that is unique with interesting physicochemical properties. The solvent properties of molten acetamide are similar to water, with high dielectric consist of 60 at 353 k. its acid – base properties are also similar to water, and it can solublise variety of organic and inorganic compounds as well. in the present studies room temperature molten liquids consisting of acetamide as one of the components have been prepared and used for various applications. Room temperature molten electrolytes consisting of magnesium perchlorate/magnesium triflate as one of the constituents have been used for rechargeable magnesium batteries where as those consisting of zinc perchlorate /zinc triflate have been used for zinc based rechargeable batteries. Full utilization of cathode material (y-mno2) is achieved using amide-based molten liquid as electrolyte in rechargeable zinc based batteries. Ammonium nitrate/ lithium nitrate containing electrolytes have been used for electrochemical super capacitors. They have been used as solvent cum stabilizers for metallic nanochains that can be used as substrate in surface enchanced Raman scattering studies.

The studies reported in the thesis deal with surface modification of non-platinum metals by coating with electronically conducting polymers, namely, polyanilne (PANI) and polypyrrole (PPY). The oxidation of Г/I2, hydroquinone/quinine and [Fe(CN)6]3-/ [ Fe(CN)6]4-are studied by cyclic voltammetry and chronoamperometry experiments. It has been shown tht the redox reactions, which do not occur on bare stainless steel electrode, occur through electron-transfer mediated by conducting polymers. The effect of heating of polyaniline (PANI) at 80 0C on its electrochemical activity is studies. Although the thermogravimetric analysis indicates that PANI is stable at temperatures up to about 250 0C and it undergoes decomposition at higher temperatures, its intrinsic redox electrochemical activity decreases with duration of heating at a temperature as low as 80 0C . The polymer completely loses its electrochemical activity. The decrease in lectrochemical activity of PANI is attributed to an irreversible loss of water molecules. The reaction order for degradation of PANI is found to be close to unity, and a value of 1.63 X 10-4 s-1 is obtained for the rate constant. The deactivated PANI does not recover its electrochemical activity even after a prolonged treatment in acidic electrolytes. The electrodeposition of PANI is carried out by galvanostatic, potentiostatic and potentiodynamic methods. The impedance data reflect a marked difference between the PANI deposited by static and dynamic methods. Furthermore, the impedance parameters vary with the sweep rate used in potentiodynamic method. Electrochemical impedance spectra of the electrodes are analyzed using a transmission line model consisting of two rails of finite resistances. Electrochemical deposition of polyaniline (PANI) is carried out on a porous carbon substrate for supercapacitor studies. PANI deposited at 100 mV s-1 sweep rate by potentiodynamic technique on porous carbon substrate is found to possess superior capacitance properties. Capacitance values as high as 1600 F g-1 are obtained and PANI coated carbon electrodes facilitate charge-discharge current densities as hgh as 45 mA cm-2 (19.8 A g-1 ). Electrodes are found to be fairly stable over a long cycle-life, although there is some capacitance loss during the initial stages of cycling. Electrooxidation of ascorbic acid on polyaniline is studied in a fuel-cell. Ascorbic acid (H2A) is employed as fuel and polyaniline (PANI) as the catalyst. H2A is an environmentally and biologically friendly molecule. The catalyst, namely PANI does not consist of any platinum group metal, and at 70 0C , a maximum power density of 4.3 mW cm-2 is obtained at a current density of 15 mA cm-2 . Also, studies on anodically deposited RuO2 for capacitor applications are reported. Cathodic deposition of RuO2 generally produces a mixture of Ru and RuO2 . On the other hand, the anodic depsotion on SS substrates is found to produce RUO2 which is characterized with high power supercapacitance properties. A capacitance value of 274 F g-1 is obtained at a current density of 20mA cm-2 .

Energijos kaupiklių kūrimas pastaraisiais metais tapo svarbia mokslo aktualija. Elektrocheminiai kondensatoriai pasižymi didesne galia, ilgesniu savaiminio išsikrovimo laiku ir didesniu darbo ciklų skaičiumi negu tradicinės elektrocheminės baterijos. Didžiausia savitąja talpa pasižymi RuO2, tačiau jo praktinį taikymą riboja didelė kaina, todėl ieškoma pigesnių pakaitalų. Pastaraisiais metais aktyviai tiriamas kobalto oksidas. Svarbu yra surasti ekonomiškai efektyvius ir paprastus metodus, leidžiančius padidinti kobalto oksidų pseudotalpas. Darbe nustatytos elektrocheminio Co nusodinimo sąlygos, kurioms esant yra formuojama pluoštinė nanostruktūra, pasižyminti dideliu paviršiaus plotu. Anodinės poliarizacijos būdu buvo suformuoti kobalto hidro/oksido sluoksniai ir ištirta jų pseudotalpa ant skirtingų substratų: nanostruktūrinės, magnetroninės-plazminės dangos ir metalurginio Co. Pseudotalpinė kobalto hidro/oksidų elgsena buvo ištirta ciklinės voltamperometrijos metodu kartu su elektrocheminėmis kvarco kristalo svarstyklėmis (EKKM). Oksidiniai sluoksniai parodė grįžtamą redukcijos-reoksidacijos ir atitinkamą pseudotalpinę elgseną. Per kelis tūkstančius anodinių ciklų buvo parodyta, kad oksidinis sluoksnis išliko stabilus. Nustatyta, kad hidro/oksidų, suformuotų ant nanostruktūrinės Co dangos, talpa maždaug 5 kartus didesnė nei suformuotų ant metalurginio Co. Šiame darbe pasiūlytas naujas kobalto oksido formavimo būdas: sulfidinės Co(OH)2–CoS kompozicijos formavimas ir... [toliau žr. visą tekstą] / Design of high efficiency energy accumulators has recently become an important issue of science and technology. Electrochemical capacitors are distinguished for a greater power, a longer self-discharge time and a greater number of work cycles as compared to those of traditional electrochemical batteries. Effective supercapacitors are mainly produced of RuO2, which is distinguished from other metals for its nearly highest specific capacity, however its practical application is limited by its high price, therefore efforts are under way to find cheaper substitutes. Recently cobalt oxide has been intensively studied. It is important to find economically effective and simple methods which will make it possible to increase the pseudocapacities of cobalt oxides. The conditions of electrochemical cobalt deposition, under which the fiber Co nanostructure possessing a great surface area is formed, have been determined in the work. Cobalt hydro/oxide layers were formed by the anodic polarization method and their pseudocapacity was studied on various substrates: nanostructured, magnetron-sputtered coating and metallurgical cobalt. The pseudocapacitor behaviour of cobalt hydro/oxides was studied by using the cyclic voltammetry method along with electrochemical quartz crystal mocrobalance (EKKM). Oxide layers showed oxidation-reduction and corresponding pseudo-capacitor behaviour.It has been shown that the oxide layer is stable and it withstands a few thousand polarization cycles. It has... [to full text]

Design of high efficiency energy accumulators has recently become an important issue of science and technology. Electrochemical capacitors are distinguished for a greater power, a longer self-discharge time and a greater number of work cycles as compared to those of traditional electrochemical batteries. Effective supercapacitors are mainly produced of RuO2, which is distinguished from other metals for its nearly highest specific capacity, however its practical application is limited by its high price, therefore efforts are under way to find cheaper substitutes. Recently cobalt oxide has been intensively studied. It is important to find economically effective and simple methods which will make it possible to increase the pseudocapacities of cobalt oxides. The conditions of electrochemical cobalt deposition, under which the fiber Co nanostructure possessing a great surface area is formed, have been determined in the work. Cobalt hydro/oxide layers were formed by the anodic polarization method and their pseudocapacity was studied on various substrates: nanostructured, magnetron-sputtered coating and metallurgical cobalt. The pseudocapacitor behaviour of cobalt hydro/oxides was studied by using the cyclic voltammetry method along with electrochemical quartz crystal mocrobalance (EKKM). Oxide layers showed oxidation-reduction and corresponding pseudo-capacitor behaviour.It has been shown that the oxide layer is stable and it withstands a few thousand polarization cycles. It has... [to full text] / Energijos kaupiklių kūrimas pastaraisiais metais tapo svarbia mokslo aktualija. Elektrocheminiai kondensatoriai pasižymi didesne galia, ilgesniu savaiminio išsikrovimo laiku ir didesniu darbo ciklų skaičiumi negu tradicinės elektrocheminės baterijos. Didžiausia savitąja talpa pasižymi RuO2, tačiau jo praktinį taikymą riboja didelė kaina, todėl ieškoma pigesnių pakaitalų. Pastaraisiais metais aktyviai tiriamas kobalto oksidas. Svarbu yra surasti ekonomiškai efektyvius ir paprastus metodus, leidžiančius padidinti kobalto oksidų pseudotalpas. Darbe nustatytos elektrocheminio Co nusodinimo sąlygos, kurioms esant yra formuojama pluoštinė nanostruktūra, pasižyminti dideliu paviršiaus plotu. Anodinės poliarizacijos būdu buvo suformuoti kobalto hidro/oksido sluoksniai ir ištirta jų pseudotalpa ant skirtingų substratų: nanostruktūrinės, magnetroninės-plazminės dangos ir metalurginio Co. Pseudotalpinė kobalto hidro/oksidų elgsena buvo ištirta ciklinės voltamperometrijos metodu kartu su elektrocheminėmis kvarco kristalo svarstyklėmis (EKKM). Oksidiniai sluoksniai parodė grįžtamą redukcijos-reoksidacijos ir atitinkamą pseudotalpinę elgseną. Per kelis tūkstančius anodinių ciklų buvo parodyta, kad oksidinis sluoksnis išliko stabilus. Nustatyta, kad hidro/oksidų, suformuotų ant nanostruktūrinės Co dangos, talpa maždaug 5 kartus didesnė nei suformuotų ant metalurginio Co. Šiame darbe pasiūlytas naujas kobalto oksido formavimo būdas: sulfidinės Co(OH)2–CoS kompozicijos formavimas ir... [toliau žr. visą tekstą]

The thesis deals with the production and evaluation of porous carbon materials for energy storage technologies, namely super capacitors and lithium sulfur batteries. / Die Doktorarbeit befasst sich mit der Produktion und Evaluierung poröser Kohlenstoffmaterialien für die Anwendung in Energiespeichertechnologien, namentlich Superkondensatoren und Lithiumschwefelbatterien.

Philosophiae Doctor - PhD / To meet a fast-growing market demand for next generation portable electronic devices with higher performance and increased device functionalities, efficient electrical energy devices with substantially higher energy, power densities and faster recharge times such as supercapacitors are needed. The overall aim of this thesis was to synthesize nanostructured sulphonated polyaniline and transition metal single, binary and ternary mixed oxide doped nanocomposites with electro-conductive properties. These nanocomposites were anchored on activated graphitic carbon and used in design of asymmetric supercapacitors. Tantalum(IV)oxide, tantalum(IV)oxide-nickel(II)oxide, tantalum(II)oxide-manganese(III)oxide, tantalum(II)oxide-nickel(II)oxide-manganese(II,III)oxide nanoparticles were synthesised using modified sol-gel methods. These were then dispersed, individually, in acidic media through sonication and incorporated in-situ into the polymeric matrix during the oxidative chemical polymerization of aniline doped with poly(4-styrene sulphonic acid). These novel polymeric nanocomposites were characterised with FTIR, UV-visible, TEM, SEM, EDS, XRD to ascertain successful polymerization, doping, morphology and entrapment of the metal oxide nanoparticles. SECM approach curves and interrogation of CV revealed that these nanocomposites are conductive and electro-active. The cells showed good supercapacitor characteristics with high specific capacitances of 170.5 Fg⁻¹ in TaO₂- PANi-PSSA, 166.1 Fg⁻¹ in TaO₂-NiO-PANi-PSSA, 248.4 Fg-1 in TaO-Mn₂O₃-PANi- PSSA and 119.6 Fg⁻¹ in TaO-NiO-Mn₃O₄-PANi-PSSA. Their corresponding energy densities were calculated as 245.5 Whg⁻¹, 179.4 Whg⁻¹, 357.7 Whg⁻¹ and 172.3 Whg⁻¹ respectively. They also gave respective power densities of 0.50 Whg⁻¹, 0.61 Whg⁻¹, 0.57 Whg⁻¹ and 0.65 Whg⁻¹ and showed good coulombic efficiencies ranging between 77.97% and 83.19%. These materials are found to have a long cycle life and therefore good electrode materials for constructing supercapacitor cells. / National Research Foundation (NRF)