Matériaux Lamellaires pour le développement de dispositifs avancés pour le stockage de l'énergie

The median scenario for global electricity demand is based on a 35% increase in demand. It is therefore necessary to develop new means of energy storage to regulate, for example, the network tensions generated by this exponential demand.This thesis presented here focuses on the development of new advanced energy devices: power batteries. It is the fruit of a consortium between the various participants in the ANR-funded "LaDHy" project, namely the Clermont-Ferrand Institute of Chemistry (ICCF), the Nantes Jean Rouxel Materials Institute (IMN) and EDF.Nowadays, existing devices are made from toxic, non-renewable and expensive materials (cobalt, lithium) that do not meet the green chemistry criteria advocated by society. Combined with the increasing scarcity of resources and geopolitical crises, the development of new materials for energy storage is a key strategic issue. The aim of this project is to develop power batteries in aqueous media based on layered materials such as double or single layered hydroxides (LDH or LSH). These materials have a number of advantages as versatility of composition of the layers and the inter-layer space, low toxicity, can be synthesized in the laboratory using soft chemistry, low cost of synthesis, reproducible and scale-up possible. These phases have already been studied for electrochemical storage, but there are still many unexplored ways, such as the use of new electrochemically active cations or the intercalation of a redox species between the layers.The first chapter is devoted to a literature review of the various energy storage methods, their how it works, their composition, advantages and disadvantages.In the second chapter, the possibility of using copper-based LDHs as electrode materials will be studied. After a bibliographical introduction, different compositions and synthesis parameters will be tested. The electrochemical characteristics of the electrode materials will be described and compared as a function of their morphology, size and porosity. The aim will also be to gain a better understanding of the structural changes that occur during cycling, leading to capacity losses.In the third chapter, the intercalation of electroactive molecules within non-electrochemically active LDH phases of the Mg-Al and Zn-Al type was carried out. The aim of this part will be to intercalate molecules with a redox potential that can be used as a positive or negative electrode. The study of electrochemical phenomena in an aqueous medium, as well as the release and its understanding, will be analyzed. The first complete two-electrode LDH-organic molecule composite cell will be produced in an aqueous electrolyte and new electrolytes, such as ionic liquids, will be tested by the IMN team.In a fourth chapter, the impact of different synthesis methods on the electrochemical properties of copper layered simple hydroxides (LSH) will be studied. The impact of morphology and nanostructuring on the capacities at first cycle and during cycling will be studied as well as the changes in structures and phases using a multi-technics approach. In addition, the intercalation of electroactive molecules within HDL phases will be studied.Finally, in the last chapter, the copper LSH phases used as a template for the synthesis of CuS will be analyzed by means of a study of the transformation kinetics. The phases resulting from these syntheses will be tested electrochemically and compared with values reported in the literature and with commercial grades.Le scénario médian pour la demande d'électricité mondiale se base sur une hausse de 35% de la demande. Il est donc nécessaire de développer des nouveaux moyens de stockage de l'énergie pour réguler par exemple les tensions de réseaux engendrées par cette demande exponentielle.Le travail de thèse présenté ici porte sur le développement de nouveaux dispositifs avancés de l'énergie : les batteries de puissance. Il est le fruit d'un consortium entre les différents acteurs du projet financé par l'ANR « LaDHy » que sont, l'Institut de Chimie de Clermont-Ferrand (ICCF), l'Institut des matériaux de Nantes Jean Rouxel (IMN) et la société EDF.Actuellement, les dispositifs existants sont composés de matériaux toxiques, non renouvelables et onéreux (cobalt, lithium) ne répondant pas aux critères de chimie verte prônés par la société. Combinés avec la raréfaction des ressources ainsi que les crises géopolitiques, l'enjeu du développement de nouveaux matériaux pour le stockage de l'énergie est un des points stratégiques importants. L'objectif porté par ce projet est de développer des batteries de puissance en milieu aqueux à base de matériaux lamellaires du type Hydroxydes doubles ou simples lamellaires (HDL ou LSH). Ces derniers possèdent de nombreux avantages comme une versatilité de composition des feuillets et de l'espace interfeuillet, une faible toxicité, synthétisables en laboratoire par chimie douce, un faible coût de synthèse, reproductible et un scale-up possible).L'étude de ces phases pour le stockage électrochimique a déjà été appréhendée mais les pistes encore non explorées restent encore nombreuses comme celle de l'utilisation de nouveaux cations électrochimiquement actifs ou bien celle qui consiste à intercaler une espèce redox entre les feuillets.Le premier chapitre est consacré à une synthèse bibliographique des différents modes de stockage de l'énergie, leurs fonctionnements, compositions, avantages et inconvénients.Dans le second chapitre, la possibilité d'utiliser les HDL à base de cuivre en tant que matériaux d'électrodes sera étudiée. Après une introduction bibliographique, différentes compostions et paramètres de synthèse seront testés. Les caractéristiques électrochimiques des matériaux d'électrodes seront décrites et comparées en fonction de leur morphologie, de leur taille, ainsi que de leur porosité. Il s'agira aussi de mieux comprendre les changements structuraux intervenant au cours du cyclage engendrant des pertes de capacité.Dans le troisième chapitre, l'intercalation de molécules électroactives au sein des phases HDL du type Mg-Al et Zn-Al non électrochimiquement actives a été réalisée. L'objectif de cette partie sera d'intercaler des molécules possédant un potentiel redox applicable en tant qu'électrode positive ou négative. L'étude des phénomènes électrochimique en milieu aqueux, de relargage ainsi que sa compréhension seront analysés. La première cellule complète à deux électrodes composites HDL-molécule organique sera réalisée en électrolyte aqueux et de nouveaux électrolytes, tels que les liquides ioniques seront testés par l'équipe de l'IMN.Dans un quatrième chapitre, l'impact de différents modes de synthèse sur les propriétés électrochimiques des hydroxydes simples lamellaire (LSH) au cuivre sera étudié. L'impact de la morphologie et la nanostructuration sur les capacités au premier cycle et au cours du cyclage seront étudiés ainsi que les changements de structures et de phases par une approche une nouvelle fois multi-techniques. De plus l'étude de l'intercalation des molécules électroactives au sein des phases HDL sera menée.Enfin, dans le dernier chapitre, les phases LSH au cuivre comme gabarit pour la synthèse de CuS seront analysées par une étude sur les cinétiques de transformation. Les phases issues de ces synthèses seront testées en électrochimie et seront comparées aux valeurs relevées dans la littérature et aux grades commerciaux

Interleaved Electroactive Molecules into LDH Working on Both Electrodes of an Aqueous Battery-Type Device

International audienceBy selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met

Understanding copper sulfide formation from layered template and their use as power electrode materials in aqueous electrolyte

International audienceCopper sulfide has received increasing attention as an electrode material in past decades. In this study, we report the synthesis of copper sulfide with layered copper hydroxide salt (LHS) (Cu2(OH)3NO3) precursors using different protocols. X-ray diffraction suggests the presence of numerous non-stoichiometric phases (Cu1-xS) and not a pure covellite phase and SEM images show particles with flower-like shape but different in size. The solidstate kinetic parameters of the reaction refined by the JMAK method indicate a pseudomorphic transformation controlled by 1D diffusion, different in term of precursors phase, reagents and protocol applied. The microwave method needs less energy to achieve the transformation than the amine digestion (AD) method and the morphology of particles is also different. Tested in sodium acetate electrolyte, CuS provides a maximum capacity of 67 mAh/g for AD, which is much higher than for the commercial grade CuS. This is explained by the difference in nanostructuration of the flower-like shape particles obtained from the layered template. Finally, CuS is used as both a positive and negative electrode material in a complete aqueous battery system but its redox process, which is strongly diffusion limited especially in the lower potential domain, prevents the whole system from operating at high power

Interleaved Electroactive Molecules into LDH Working on Both Electrodes of an Aqueous Battery-Type Device

By selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met

Electrochemical Behavior of Morphology-Controlled Copper (II) Hydroxide Nitrate Nanostructures

International audienceNanostructure control is an important issue when using electroactive materials in energy conversion and storage devices. In this study, we report various methods of synthesis of nanostructured copper (II) hydroxide nitrate (Cu-2(OH)(3)NO3) with a layered hydroxide salt (LHS) structure using various synthesis methods and investigate the correlation between nanostructure, morphology, and their pseudocapacitive electrochemical behavior. The variations in nanostructure size and morphology were comprehensively explored by combining X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the electrochemical activity was characterized using cyclic voltammetry. We demonstrate that Cu-2(OH)(3)NO3-LHS nanostructured submicron particles produced by alkaline precipitation with 88% of the copper cations can cycle with a two-electron redox process. Unfortunately, the electroactivity decreases rapidly from the first cycle due to the occurrence of structural transformations and subsequent electrochemical grinding. However, samples obtained by ultrasonication and microwave synthesis, two original synthesis methods for LHS materials, formed of nanosized crystalline domains agglomerated in micron-sized particles, represent a good compromise between capacity and cyclability. Moreover, by using pair distribution function analysis on electrode materials after repeated cycling, we were able to follow the chemical and structural changes occurring in Cu-2(OH)(3)NO3 materials during electrochemical cycling with first a quick transformation to Cu2O and then the appearance of Cu metal and copper acetate Cu(II)(2)(O2CCH3)(4)center dot 2H(2)O

Intercalated Organic Redox-active Anions for Enhanced Capacity of Layered Double Hydroxides

International audienceA Layered Double Hydroxide (LDH) compound LDH ([Mg 2 Al(OH) 6 ] + x 2 H 2 O) intercalated with a redox active organic anion, Anthraquinone-2-sulfonate (AQS), has been envisioned as an electrode material for high power aqueous based battery. The purpose is to use this interlayer redox active molecule for the enhancement of the specific capacity at the LDH composite electrode, which should allow fast charge transfer at the negative electrode for high power storage applications. This is achieved by the reduction of AQS in charge and oxidation in discharge within a redox inactive LDH matrix. The first charge of this new material [Mg 2 Al(OH) 6 ] + [AQSO 3 ] − x 2 H 2 O leads to a capacity of 100 mAh g −1 at − 0.78 V vs Ag/AgCl (based on the weight of the active material) when operated in aqueous 1 M sodium acetate electrolyte. However, low cycling stability was observed, since a drastic loss in specific capacity occurs after the first charge. This study focuses at elucidating the mechanism behind this phenomenon via in situ UV/vis experiments. Subsequently, the dissolution of charged AQS anions into the electrolyte during the first charge of the anode has been identified and quantified. Such understanding of fading mechanism might lead to the design of improved LDH-based electrodes, which utilize redox active anions working in the positive potential range with enhanced cycling ability