Transposition of a weighted ah-throughput model to another li-ion technology: is the model still valid? new insights on the mechanisms

The increasing interest in electric vehicles powered by rechargeable batteries, combined with the wide development of powerful lithium-ion batteries as a renewable energy storage system have raised the need for battery ageing characterization. Several models have been developed for this purpose, including empirical, fatigue and mathematical ones. One of the main issue of these approaches consists of the universality, when extension is required to other chemistries or solicitations. Electrochemical models are supposedly the most extensible. The Weighted Ah-Throughput Model takes into account that certain operating conditions may lead either to an increase or a decrease of the rate of ageing. It modulates the impact of the exchanged Ah by the temperature, the C-rate and the state of charge (SOC), both in calendar and active regime. This influence of the parameters is described here, and compared between two Li-ion chemistries: LFP and NCA. The similitudes enable us to extract the generic hidden mechanisms that, by nature, the fatigue modelling methods do not provide. This innovative method enables us to reach energetic behavior laws. We finally suggest improvements on the tests matrix used to define the model, to better fit the outcome of the study

A large electrochemical setup for the anodization of aluminum towards highly ordered arrays of cylindrical nanopores

A new electrochemical setup and the associated procedures for growing ordered anodic aluminum oxide pore arrays on large surfaces are presented. The typical size of the samples is 14 × 14 cm2. The most crucial experimental parameters that allow for the stabilization of the high-field procedures are a very efficient cooling of sample and electrolyte, as well as the initial ramping up of the voltage at an accurately defined rate. The morphology of the cylindrical, parallel alumina pores is similar to those obtained on smaller scales with standard setups. Our setup facilitates the availability of porous anodic alumina as a template system for a number of applications

An electrochemically functional layer of hydrogenase extract on an electrode of large and tunable specific surface area

Electrode supports are generated by electrospinning of polyacrylonitrile fibers and subsequent coating of a thin electrically conductive TiO2 layer by atomic layer deposition. The supports are then functionalized with a [NiFe]-hydrogenase-containing membrane fraction from Escherichia coli and are characterized structurally and electrochemically. The hydrogenase suspension generates a micron-thick organic film around the fiber mat, which exhibits electrocatalytic activity for hydrogen evolution. Furthermore, the electrode geometric surface area is varied systematically via the electrospinning procedure, which reduces the charge transfer resistance and increases the hydrogen evolution current density to >500 μA cm−2 at 0.3 V overpotential

Functionalization of nanostructured substrates for energy conversion and storage

Afin de répondre au besoin de la société actuelle qui utilise toujours plus de moyens de transport et de dispositifs portables, les modes de production, de conversion et de stockage de l'énergie, sont en train de connaître de véritables mutations. Afin de créer des systèmes capables de générer une énergie maîtrisée et renouvelable, les nanosciences et nanotechnologies sont des domaines de premier plan. Le travail présenté dans ce manuscrit décrit la fabrication de structures, de taille nanométrique, organisées à grande échelle. La fonctionnalisation se fait par synthèse de films ou de particules par ALD. Des systèmes MIM sont synthétisés sur des structures ordonnées d'alumine poreuse. Les matériaux déposés en couches minces sont TiN, Al2O3 et HfO2. L'objectif est de fabriquer des nano-condensateurs à hautes performances pouvant être utilisés pour des applications de stockage de données, de mémoire ou pour le stockage d'énergie dans des petits dispositifs comme la technologie RFID.Dans une deuxième partie, des catalyseurs métalliques Pd/Ni sont déposés sur des membranes d'alumine pour l'électro-oxydation de l'acide formique. De la même manière, des nano-tubes de TiO2 fabriqués par oxydation anodique sont fonctionnalisés par des nano-particules de Pd pour l'électrooxydation de l'éthanol. Ces deux études systèmes peuvent conduire à leur utilisation comme catalyseurs au niveau de l'anode des piles à combustible liquide à combustion directe. Enfin, la dernière partie de ce travail consiste au dépôt par voie électrochimique de Cu2O, sur des nano-tubes de TiO2 qui servent de support. La jonction p/n ainsi fabriquée pourra servir pour la photo-conversion de l'énergie solaire.In order to meet the growing needs in today's society that requests more transportation and portable devices, energy production, conversion and storage systems are now experiencing real changes. To fabricate systems able to generate a controlled and renewable energy, nanoscience and nanotechnology are leading research fields. The work presented in this manuscript describes the fabrication of nanosized, large-scale organized structures. These nanostructures have been functionalized through film and particle synthesis using a chemical vapor deposition method: the Atomic Layer Deposition (ALD).Thus, metal/insulator/metal (MIM) systems are fabricated on highly-ordered high-aspect ratio porous alumina. The materials that have been deposited are TiN, Al2O3 and HfO2. The aim is to produce high performance nanocapacitors that can be used for data storage (DRAM) application or for energy storage in small devices such as RFID.In a second part, metallic catalysts such as Pd/Ni have been deposited on alumina membranes for formic acid electro-oxidation. Similarly, TiO2 nanotubes have been fabricated by anodic oxidation and they have been functionalized with Pd nanoparticles for ethanol electro-oxidation. Both studied systems can be used as anode catalysts in direct liquid fuel cells.Finally, the last part of this work has consisted in the study of Cu2O, as a p-type semiconductor, that has been electrochemically deposited onto TiO2 nanotubes (n-type semiconductor). The resulting p/n junction can be interesting for solar energy photoconversion

Transposition of a weighted ah-throughput model to another li-ion technology: is the model still valid? new insights on the mechanisms

The increasing interest in electric vehicles powered by rechargeable batteries, combined with the wide development of powerful lithium-ion batteries as a renewable energy storage system have raised the need for battery ageing characterization. Several models have been developed for this purpose, including empirical, fatigue and mathematical ones. One of the main issue of these approaches consists of the universality, when extension is required to other chemistries or solicitations. Electrochemical models are supposedly the most extensible. The Weighted Ah-Throughput Model takes into account that certain operating conditions may lead either to an increase or a decrease of the rate of ageing. It modulates the impact of the exchanged Ah by the temperature, the C-rate and the state of charge (SOC), both in calendar and active regime. This influence of the parameters is described here, and compared between two Li-ion chemistries: LFP and NCA. The similitudes enable us to extract the generic hidden mechanisms that, by nature, the fatigue modelling methods do not provide. This innovative method enables us to reach energetic behavior laws. We finally suggest improvements on the tests matrix used to define the model, to better fit the outcome of the study