The particle size distribution of a powder plays a crucial role in the performance of bat- teries with powder-based electrodes and requires reliable and practical analysis. The aim of this project was therefore to develop a protocol for analysis of the particle size dis- tribution and composition of powders used in the electrodes of Nilar’s batteries. The analytical methods described in the protocol permits practical applications, such as com- paring the particle size distribution and composition of pristine and reclaimed powders with the manufacturer’s data as quality control.  A literature survey was initially conducted to select appropriate analysis methods for this project. After performing several practical trials, X-ray diffraction, X-ray fluorescence, laser diffraction analysis, and scanning electron microscopy were the techniques included in the protocol. X-ray diffraction showed potential in obtaining the crystallite size of the powders, but other techniques are required to confirm the results. X-ray fluorescence analysis was found to produce fairly similar values as those given by the manufacturer. Scanning electron microscopy was used to analyse the particle size distribution with the help of an image processing software. Complementary data of the smaller particle sizes was obtained using laser diffraction analysis.

In this study, the effects of electrode microstructure and electrolyte parameters on intermediate temperature solid oxide fuel cell (ITSOFC) performance were investigated using a one-dimensional SOFC model from the Pacific Northwest National Laboratory (PNNL). After a brief review of the fundamental SOFC operating processes and a literature review incorporating more advanced SOFC topics, such as electrode microstructure modeling and mixed ionic and electronic (MIEC) composite cathodes, it was determined from the PNNL benchmark results that the dominating ITSOFC losses were caused from the activation and Ohmic overpotentials. The activation overpotential was investigated through the exchange current density term, which is dependent on the cathode activation energy, the cathode porosity, and the pore size and grain size at the cathode triple phase boundary (TPB). The cathode pore size, grain size, and porosity were not integrated in the PNNL model, therefore, an analytical solution for exchange current density from Deng and Petric (2005) was utilized to optimize their effects on performance. The Ohmic loss was determined to be entirely dependent on the electrolyte ionic conductivity, and an optimal value for this conductivity was determined. Simultaneous optimization of the above parametric evaluations led to a 388 % increase in performance from the PNNL benchmark case at 600 °C. Although this was deemed successful for this project, future research should be focused on numerically quantifying and modeling the electrode microstructure in two and·three-dimensions for more accurate results, as the electrode microstructure may be highly multi-dimensional in nature.

This Diploma Thesis is focused on investigation of the voltammetric behavior of the explosive penthrite (pentaerythritol tetranitrate) (PETN) and on searching for optimum conditions for its determination using differential pulse voltammetry (DPV) at a hanging mercury drop electrode (HMDE) (this part of the Diploma Thesis follows the topic investigated in the author's Bachelor Thesis; in this Diploma Thesis, the results of the Bachelor thesis are applied to the determination of PETN in environmental matrices) and at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and on investigation of voltammetric behavior in real samples (deionized, drinking, and river water). For investigating the behavior of PETN in aqueous-methanolic media on the m-AgSAE, mixtures of Britton-Robinson buffers (BR-buffers) and methanol in various volume ratios were used. In non-aqueous media, methanolic solutions of tetramethylammonium bromide (TMAB), tetrabutylammonium iodide (TBAI), and tetrabutylammonium chloride (TBAC) were used as supporting electrolytes. Firstly, the influence of pH (in the range of 2 - 13) and methanol content (10 - 90 vol. %) on voltammetric responses of PETN was studied. The best response was obtained at each of those pH values at the volume ratio of BR-buffer - methanol of 1:9 or...

L’objectif de ce travail est d'envisager les modifications de formulation ou de procédé dans la technologie de geltrusion développée par Batscap pour augmenter la fiabilité des supercondensateurs en limitant l'autodécharge. La technologie repose sur l’extrusion simultanée de polymères (PVDF, PVDF-HFP), d’un solvant (PC) et de charges (CA, NC). Le mélange réalisé en extrusion bivis est ensuite filmé et laminé sur le collecteur en aluminium. Dès lors, il a été fondamental de chercher à comprendre les interactions entre les différents composants de l’électrode, avec l’étude de la miscibilité du système ternaire polymère/polymère/solvant puis l’étude de l’adsorption du solvant sur les charges. Cette démarche a permis une meilleure compréhension des phénomènes impliqués en passant par une caractérisation approfondie du complexe, dans sa formulation actuelle aux différentes étapes du procédé. Ensuite, des modifications de formulations ont été envisagées. En particulier, l'effet de la structure et de la masse molaire des polymères sur l’adhésion a été étudié. Dans tous les cas, il a été envisagé de tester les possibilités offertes par l'utilisation d'un solvant différent (DMSO). Ce dernier étant un meilleur solvant du PVDF est plus facile à éliminer que le PC. Enfin, à partir des données rhéologiques du mélange, une modélisation mécanique, en utilisant le modèle de Maxwell à plusieurs temps de relaxation, a été menée dans l'opération de laminage du mélange en prenant en compte un comportement viscoélastique du gel. Toutes ces études ont permis de conclure sur les modifications pertinentes de la formulation ainsi que des conditions du procédé / The objective of this work is to consider changes in formulation or process of the geltrusion technology developed by Batscap to increase the reliability of supercapacitors by limiting self-discharge. The technology is based on the simultaneous extrusion of polymers (PVDF, PVDF-HFP), solvent (propylene carbonate) and fillers (activated carbon, carbon black). The mixture carried out in a twin-screw extrusion is then filmed and laminated on the aluminium collector. Therefore, it was important to understand the interactions between the different components of the electrode, and especially to study the miscibility of the ternary system polymer/polymer/solvent and also the adsorption of solvent on fillers. This approach has allowed a better understanding of the phenomena involved through a characterization of the complex, in its current form at different stages of the process. Then, changes in formulations were considered. In particular, the effect of the structure and molecular weight of the polymers on adhesion was studied. In all cases, it was envisaged to test the possibilities offered by the use of a different solvent (dimethyl sulfoxide). The latter being a better solvent for the PVDF, is also easier to remove than propylene carbonate. Finally, from the rheological data of the mixture, a mechanical modeling, using the multimodal Maxwell model, was conducted in the lamination step taking into account of the viscoelastic behavior of the gel. All these studies allow us to conclude on the relevant changes in the formulation and process conditions

This thesis deals with the determination of carvacrol, thymol, and eugenol by HPLC with electrochemical detection. Carbon paste electrode and boron doped diamond film electrode were used as the working electrodes. For the comparison, UV spectrophotometric detection at 275 nm was used besides the electrochemical detection. The separation was performed on LiChroCART 125-4, RP-18e (5 µm) column. Optimum separation conditions were found: mobile phase consisting of acetonitrile and acetate buffer in ratio 50:50, the optimum buffer pH was pH 5. The optimum potential of working electrode during electrochemical detection was +0,8 V and +1,2 V for carbon paste electrode and boron doped diamond film electrode, respectively. For both electrodes, repeatability of the measurement was examined; the surface of both electrodes had to be renewed between the measurements. Under the obtained optimum conditions, calibration dependences were measured. The studied substances were determined in real samples, in Thymus vulgaris L. and Achillea millefolium L. and in thyme-containing tea and syrup.

Presented Diploma Thesis deals with the study of electrochemical behavior of 5-nitroimidazole (5-NI), with the search for optimal conditions for its determination using techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and at a boron-doped diamond film electrode (BDDFE), and with the comparison of reached limits of quantification (LQs). The optimal conditions found for measuring calibration dependences of 5-NI at the m-AgSAE in deionized water were as follows: Britton-Robinson buffer of pH 7.0 and 10.0 for DCV and DPV, respectively. At both thechniques, it is advisable to use an electrochemical regeneration of the electrode surface by the application of a couple of regeneration potentials Ereg,1 = 0 mV and Ereg,2 = −800 mV. The calibration dependences were measured in the concentration range from 1·10−6 to 1·10−4 mol·l−1 , with the LQs of 1.0·10−6 mol·l−1 for DCV at the m-AgSAE and 1.5·10−6 mol·l−1 for DPV at the m-AgSAE. The concentration dependences of 5-NI at the BDDFE were measured using the DCV technique in the BR buffer of pH 3.0. For the DPV technique, the optimal medium seemed to be the BR buffer of pH 2.0, however, because of the presence of an interfering peak in the supporting electrolyte,...

This thesis deals with electrochemical behaviour of tauroursodeoxycholic acid (TUDCA) at silver solid amalgam electrode modified by mercury meniscus (m-AgSAE), polished silver solid amalgam electrode (p-AgSAE) and hanging mercury dropping electrode (HMDE). This thesis is a part of a bigger scientific research that deals with synthesis and characterization of supramolecular systems based on natural steroid compounds and its conjugates. TUDCA offers one reduction peak at m-AgSAE in the environment of Britton - Robinson buffer in range of pH 6.0 - 13.0. The potential of this peak is around −1200 mV. Using cyclic voltammetry was determined that the process on the electrode surface is quasireversible, the reduction is controlled by diffusion and the anodic process is controlled by adsorption. Concentration dependence measured at HMDE by direct current voltammetry in 0.04 mol∙l-1 borat buffer (pH 9.1) is linear in two concentration intervals - 1∙10-3 - 2∙10-4 mol∙l-1 and 1∙10-4 - 8∙10-6 mol∙l-1 of TUDCA. There was no linear dependence between the increase of concentration of TUDCA and the height of the peak obtained on amalgam electrodes by methods DC, DP, cyclic and "square-wave" voltammetry. On HMDE was in several short concentration intervals measured by a CV method a linear dependence of cathodic and...

Differential pulse voltammetry (DPV) was used for developing a method for the determination of phenothiazine derivatives, namely chlorpromazine (CHP) and levomepromazine (LMP), using a glassy carbon electrode (GCE) and a graphite electrode, both with a 2 mm disc diameter. Comparison of quantification limits (LQ) for both substances on both electrodes was performed. After optimizing and processing the results, the optimal conditions for measuring calibrations were as follows: Britton- Robinson (BR) buffer at pH 4.0. Calibration dependences were measured inthe concentration range from 1·10-7 to 1·10-4 mol·dm-3 . There was no need for electrochemical electrode regeneration or matrix pretreatment. The results showed higher measurement sensitivity for CHP, and the graphite electrode also showed higher sensitivity. Although there were measured lower concentrations with the graphite electrode in comparison to the GCE, because of the low repeatability of the measurements in the lower concentration range 1-10·10-7 mol·dm-3 , the LQ is comparable to the results reached on the GCE. Besides to the BR buffer, measurements in other matrices (drinking water and river water) were also made. The following LQ values were achieved: 1.0·10-6 mol·dm-3 (in BR buffer), 1.1·10-6 -1.4·10-6 mol·dm-3 (in drinking water) and...

Afin de pallier les problèmes de sécurité posés par l'emploi d'électrolytes liquides, des batteries incorporant des électrolytes solides ont été envisagées, conduisant à des dispositifs « tout solide » de type microbatterie au lithium. Dans le cas de ces systèmes, des études concernant les phénomènes aux interfaces restent à développer, afin de comprendre les processus limitants qui se déroulent à l'échelle atomique, similairement à la formation de la SEI (« Solid Electrolyte Interface »), bien connue dans le cas de l'utilisation d'électrolytes liquides. Dans ce type de problématiques, l'apport des méthodes de la chimie calculatoire, de part leur aspect prédictif et explicatif, est incontestable. Le présent travail de thèse, en prenant pour objet d'étude l'électrolyte solide LixPOyNz, se place dans ces problématiques, en proposant l'étude fondamentale de modèles d'interfaces électrode/électrolyte. L'électrolyte considéré étant un matériau amorphe, le premier verrou à lever consiste en la recherche d'un modèle de ce système, apte à simuler les propriétés électroniques de l'électrolyte réel, constituées par des données XPS cibles. Les calculs menés, visant à la modélisation des spectres XPS, ont permis tout à la fois de proposer un modèle de l'électrolyte et de mettre en lumière l'existence d'une coordinence des atomes d'azote non considérée jusqu'alors dans l'interprétation expérimentale des données XPS. La possible existence d'atomes d'azote monovalents au sein de l'électrolyte semble confirmée par des calculs vibrationnels, thermodynamiques et cinétiques complémentaires, tandis que ce résultat permet de réviser la vision communément admise de la structuration de l'électrolyte LixPOyNz et de la diffusion des ions Li+ au sein de celui-ci. Enfin, ce modèle structural de l'électrolyte a été employé à la simulation d'une interface électrode/électrolyte (LixPOyNz/Si). Une considération particulière a notamment été apportée à l'étude de l'adsorption du modèle à la surface et de la diffusion des ions lithium au sein de l'interface. / In order to overcome the safety issues induced by the use of liquid electrolytes, Li-ion batteries involving solid electrolytes have been considered, leading to an ‘all-solid’ kind of devices, commonly called microbatteries. For such devices, studies on the limiting processes that take place at electrode/electrolyte interfaces need to be done, to understand the electrochemical phenomenons likely to occur at the atomic scale, similarly to the well-known SEI formation. In this goal, methods of computational chemistry can provide both explanatory and predictive breakthroughs. The present work takes part in those issues by intending a study of electrode/electrolyte interfaces, considering LixPOyNz as the solid electrolyte material. Owing to the amorphous structuration of this system, the first barrier to break consists in the search for a suitable model, able to reproduce its real XPS electronic properties. Modelling of XPS spectra has both lead to propose a model of the electrolyte and highlight the possible existence of a new coordinence for nitrogen atoms, up to now unconsidered experimentally. Complementary calculations of Raman spectra, thermodynamic and kinetic data tend to evidence this coordinence, leading to a refinement of the commonly considered diffusion scheme. Finally, this structural model has been used to simulate an electrode/electrolyte interface (LixPOyNz/Si), with the particular aim of studying its adsorption on the electrode and the Li-ion diffusion through the interface.

Une cellule photovoltaïque organique est constituée d’une couche photoabsorbante comprise entre deux électrodes dont l’une au moins est transparente. Généralement, les cellules sont illuminées au travers de l’électrode inférieure transparente d’oxyde d’indium dopé à l’étain (ITO). Néanmoins, de nombreuses applications comme l’automobile nécessitant un éclairage par le dessus du module, nous nous sommes intéressés à l'élaboration de cellules photovoltaïques sur substrat flexible, avec l'électrode inférieure opaque et l'électrode transparente déposée sur le dessus de la cellule. Deux types d'architectures ont été développés. Dans le premier cas, la cellule solaire organique finale a été entièrement déposée par des techniques de dépôt en voie liquide avec les deux électrodes en PEDOT:PSS imprimées par jet d’encre. Dans le second cas, les cellules ont été élaborées sur électrode d'argent avec une électrode supérieure transparente tricouche oxyde/métal/oxyde (MoO3/Ag/MoO3) évaporée thermiquement. Les cellules solaires organiques réalisées selon la seconde architecture ont été connectées en série afin de créer un module photovoltaïque organique. Ce dernier a permis d’alimenter et de faire briller une LED. / An organic solar cell is made of a photoactive layer sandwiched between two electrodes among which one at least is transparent. Usually, solar cells are illuminated through the tin-doped indium oxide (ITO) bottom transparent electrode. Nevertheless, many applications like automobile requiring illumination from above the module, we designed photovoltaic cells on a flexible substrate, with an opaque bottom electrode and a top transparent one. Two types of architectures were developed. At first, the final organic solar cell was fully deposited by solution-process with both electrodes made of ink-jet printed PEDOT:PSS. Then the cells were elaborated on a silver bottom electrode with a transparent evaporated oxide/metal/oxide (MoO3/Ag/MoO3) top electrode. The organic solar cells made according to the second structure were connected in series to create an organic photovoltaic module. It allowed to power and shine a white LED.