L’objectif de ce travail a été de mettre en place un système original capable de produire et stocker l’énergie à partir de la lumière dans un dispositif unique. Pour ce faire, nous avons choisi d’adapter l’électrode photo-sensible d’une DSSC sur un système d’accumulateur électrochimique. La première partie de ce travail a été de mettre en place la technique de spectroscopie EIS-λ, basée sur la spectroscopie d’impédance électrochimique couplée à un balayage en longueur d’onde de la lumière incidente. L’objectif de cette mesure est d’identifier et de quantifier les différents mécanismes de transfert électroniques, photo-dépendant ou non, ayant lieu à la surface de l’électrode photo-sensible, ainsi que les processus de désactivation des états excités des sensibilisateurs. Nous nous sommes ensuite penchés sur la recherche des conditions optimales d’utilisation de deux coadsorbants — l’acide bismethoxyphenyl phosphinique ou BMPP et l’acide chenodesoxycholique ou CDCA — avec le sensibilisateur de référence N719. Nous avons également quantifié leurs activités shield et anti-π-stacking grâce à la technique EIS-λ. Nous avons ainsi réalisé une DSSC présentant un rendement de photo-conversion de 8,3% en utilisant le co-adsorbant BMPP dans un ratio [co-ads]/[S] = 1, contre 7,2% dans les conditions de référence — avec le coadsorbant CDCA utilisé dans un ratio [co-ads]/[S] = 10. Par la suite, nous avons imaginé et synthétisé trois complexes de ruthénium hydrophiles originaux dont nous avons testé le pouvoir de photo-conversion dans des DSSC à électrolyte 100% aqueux, en présence des co-adsorbants sélectionnés. Ces systèmes ont permis de dépasser le pouvoir de photo-conversion du sensibilisateur N719, dans l’eau, avec un rendement maximal obtenu de 1,31%. Enfin, nous avons sélectionné la meilleure combinaison sensibilisateur / co-adsorbant afin de réaliser une électrode photo-sensible que nous avons implémentée dans un système original d’accumulateur électrochimique à base d’électrolytes aqueux. Le système ainsi mis en place constitue aujourd’hui le premier dispositif fonctionnel d’accumulateur 100% aqueux photo-rechargeable à partir d’une électrode mésoporeuse photo-sensibilisée / The aim of this work was to imagine and to develop a new system able to produce and store energy from sunlight in a single device. For this purpose, the photo-sensitive electrode of a DSSC has been adapted to an electrochemical accumulator. The first part of this work was to develop a new spectroscopic technique, called EIS-λ and based on electrochemical impedance spectroscopy combined to incident light wavelength sweep. This technique has proved its capacity to identify and quantify the different mechanisms of electron transfer over the surface of the semiconducting material and their dependency to incident wavelength, together with the various deactivation processes of the excited state of the sensitizer. Then, we investigated the best conditions to use two different co-adsorbents — namely bis-methoxyphenylphosphinic acid, or BMPP, and chenodesoxycholic acid, or CDCA — with the reference sensitizer N719. The shield and anti-π-stacking activities of the two coadsorbents has been characterized using EIS-λ technique. DSSC with a photo-conversion yield of 8,3% has been prepared in the lab using BMPP in a ratio [co-ads]/[S] = 1 while reference conditions – namely with CDCA in a ratio [co-ads]/[S] = 10 — only gave 7,2%. Besides, we have designed and synthesized three original hydrophilic ruthenium complexes, then tested their photo-conversion properties in DSSC with 100% aqueous electrolytes. Such systems, with the selected co-adsorbents, allowed 1,31% photo-conversion yield to be obtained, which is two times larger than the efficiency exhibited by N719 in the same electrolyte conditions. Finally the best combination sensitizer / co-adsorbent has been selected to achieve a photo-sensitive electrode which has been implemented in an original electrochemical accumulator with aqueous electrolytes. This system represents the first functional device of a 100% aqueous accumulator, which is photo-reloadable with a photosensitized mesoporous electrode

Ionic conductivity of solid polymer electrolytes (SPEs) can be enhanced by the addition of fillers, while maintaining good chemical stability, and compatibility with popular cathode and anode materials. Additionally, polymer composite electrolytes can replace the flammable organic liquid in a lithium-ion battery design and are compatible with lithium metal. Compatibility with Li-metal is a key development towards a next-generation rechargeable Li-ion battery, as a Li-metal anode has a specific capacity an order of magnitude higher than LiC6 anodes used today in everyday devices. The addition of fillers is understood to suppress the crystalline fraction in the polymer phase, increasing the ionic conductivity, as Li-ion conduction is most mobile through the amorphous phase. A full model for a conduction mechanism has not yet constructed, as there is evidence that a semi-crystalline PEO-based electrolyte performs better than a fully amorphous electrolyte. Furthermore, it is not yet fully understood why the weight load of fillers in PCEs can range from 2.5%wt to 52.5%wt, in order to achieve high ionic conductivity (~10-4S/cm). This work seeks to investigate the conduction mechanism in the PCE through the use of doped-Li7La3Zr2O12 as a filler and analysis of the PCE microstructure. In this work, a solid-state electrolyte, doped-Li7La3Zr2O12 (LLZO) was synthesized via a sol-gel method, and characterized. The effect of doping and co-doping the Li, La and Zr sites in the LLZO garnet was investigated. A PEO-based polymer composite electrolyte (PCE) was prepared by adding bismuth doped LLZO (Li7-xLa3Zr2-xBixO12) as a filler. The bismuth molar ratio was changed in value to study the dopant role on the bulk PCE ionic conductivity, polymer phase crystallinity and microstructure. Results suggest that small variations in dopant can determine the optimal weight load of filler at which the maximum ionic conductivity is reached. By understanding the relationship between filler properties and electrochemical properties, higher performance can be achieved with minimal filler content, lowering manufacturing costs a solid-state rechargeable Li-ion battery.<br>

This Diploma thesis is focused on physical and chemical effects which contribute to the decomposition of organic dyes by diaphragm discharge generated in water solutions. Due to the application of DC high voltage source in continuous regime, there is an effect of electrolysis contributing to the dye decomposition by diaphragm discharge. The aim of this work was to find out when the electrolysis is running (or when is the moment of discharge breakdown) and which factors influence the breakdown. The other goal was decomposition of selected textile and food organic dyes by electrolysis itself. In the theoretical part, theory about creation of electrical discharges in aqueous solutions is noted and various types of underwater discharges are described. Background researches about underwater electrical discharges used in the world are mentioned as well as the use of diaphragm discharges and various ways how to remove organic dyes from wastewater. Finally, theories of electrolysis, UV-VIS spectroscopy and basis of other analytical methods useful for detection of organic molecules are described. Experimental part is oriented to experiment procedure which was carried out in a reactor with separated electrode areas. Separation was made by dielectric diaphragm with a pinhole in the centre. Its initial diameter was 0.4 mm. Used chemicals and course of experiments are described in this part, too. First, the breakdown moment in the reactor was investigated (i. e. determination, when only electrolysis was operating) by formation of hydrogen peroxide and measurement of dynamic (time resolved) electrical characteristics. Next, decomposition of selected dyes by electrolysis was carried out. As the decomposition was related to decolorization of the solution, UV-VIS spectroscopy in the range of 350–700 nm was used for determination of dye concentration. Next part focused on results presents various factors which had an effect on breakdown of diaphragm discharge. These factors are kind of used electrolyte, initial conductivity of solution, kind of dye, temperature of solution and type of reactor (or solution volume). From the result, the most important factor is initial solution conductivity. After the determination of the breakdown moment, the electrolysis of organic dyes was performed. The applied current was 10 mA, initial conductivity was 500 µS/cm and used electrolyte was NaCl. Moreover comparison of dye decomposition in dependence on the different applied power was realized. From this comparison one can assume, there is no significant contribution of electrolysis (the efficiency is approximately 15 %) to the diaphragm discharge in aqueous solution.

The exact mechanism of the discharge in liquids ignition is not sufficiently known up to now. Although during the last years was achieved the great progress and overloading which some of them are written in this theoretical part of thesis. This thesis is divided into two experimental parts. When the first part deals with diagnostics of diaphragm discharge in electrolyte solutions and the second part is focused on its use for uncoiling (higher homogenization) of carbon nanotubes in solutions. In experiment 1, three different sized (4 l, 100 ml, 50 ml) diaphragm discharge configurations were used to diagnose diaphragm discharge in electrolyte solutions. Diagnostics is done through current and voltage waveforms with the addition of synchronized ICCD camera images that have been connected to a four-channel oscilloscope. The V-A characteristic can be described by three events occurring in the electrolyte solution with a gradual increase in voltage. Slowly increasing of the voltage in the solution leads first to electrolysis. The next phase is the formation of microbubbles or bubbles, which is characteristic of the curve by a slight decrease in the increase of the current passing between electrodes. The sudden increase in the current flow is characteristic of the last phase, namely the discharge phase. The distance of the electrodes from the diaphragm does not significantly affect the V-A characteristic. The higher diameter of the pin hole, therefore, has a higher voltage, but this does not affect the origin of bubble generation or breakdown. The higher thickness of diaphragm, the higher voltage is needed to the beginning of the bubbles generation, and consequently the discharge breakdown. Comparison of the voltage of the start generation of the bubbles and breakdown for PET diaphragms and diaphragms from the ceramic there was no mark able difference. One of the most important parameters is the conductivity of the electrolyte solution. The lower voltage is needed for the start generation of the bubbles at the higher solution conductivity, and also the discharge generation is observed at a lower breakdown voltage. The second experimental part is focused on the study of the diaphragm discharge effect on carbon nanotubes. A specially designed U-shaped reactor is used to modify carbon nanoparticles. Tap water and aqueous solutions of organic compounds are used as the electrolytic solutions. The discharge is generated by a non-pulsed DC high source with a voltage in the range of 0-2.8 kV supplied to platinum electrodes located in the electrolyte solution. The experimental results have shown that the diaphragm discharge has positive effects on the disintegration of clusters and agglomerates of carbon nanotubes. The primary effect on disintegration is probably the shock waves generated by the discharge. It turned out that it depends on the electrode configuration, where the treatment in anode space has far greater effects than the treatment in cathode half of the reactor. Effects of carbon nanotubes disintegration in solution are long-lasting and the treatment effect is not loosed after several months. There were detected no significant changes in the structure of plasma-treated nanotubes by Infra-red spectroscopy.