Polycationic oxides for supercapacitors with high volumetric energy density

Les supercondensateurs sont des dispositifs de stockage électrochimique de l’énergie très intéressants lorsque des pics de puissance sont mis en jeu. Toutefois, leur densité d’énergie volumique est la principale limite pour leur intégration, en particulier, dans des systèmes de transport terrestre. L’utilisation de matériaux d’électrode ayant un comportement pseudocapacitif et des masses volumiques élevées permettrait d’améliorer la densité d’énergie volumique des supercondensateurs. Avec cet objectif, des dispositifs à base des matériaux de la famille Ba0,5Sr0,5CoxFe1-xO3-δ, nommés BSCFs, ont été développés dans le cadre de cette thèse. Plusieurs compositions de cette famille d’oxydes ont été préparées par un procédé glycine-nitrate et ont été testés comme matériau actif d’électrode positive en milieu aqueux neutre. La capacité volumique de ces matériaux s’avère être beaucoup plus élevée que celle des carbones activés utilisés dans les supercondensateurs commerciaux. Elle a montré également dépendre de la composition en cobalt et en fer, du régime de charge, de la nature de l’électrolyte… Le mécanisme de stockage de charges dans ces matériaux a été exploré grâce à des techniques in situ (absorption des rayons X) et operando (diffraction des rayons X) effectuées aux synchrotrons SOLEIL (France) et SPring-8 (Japon). Enfin, des dispositifs associant une électrode positive à base de BSCF et du carbone activé ou FeWO4 en tant qu’électrode négative ont démontré l’intérêt d’intégrer de tels matériaux pour améliorer la densité d’énergie volumique des supercondensateurs.Supercapacitors are attractive electrochemical energy storage devices for high power applications. However, volumetric energy density is the main limitation for their integration in such applications as terrestrial transport systems. The use of high density pseudocapacitive oxides as electrode material could lead to a volumetric energy density improvement. With this aim, materials from Ba0,5Sr0,5CoxFe1-xO3-δ family, so called BSCFs, have been studied. Several compositions have been prepared and evaluated as positive electrode materials in aqueous neutral electrolyte. Volumetric capacitances have shown to be greater than those of activated carbons, already used in marketed supercapacitors. They have also shown to depend on cobalt and iron ratio, charge rate, electrolyte composition... The study of the charge storage mechanism in these materials has been investigated thanks to in situ (X-Ray absroption spectroscopy) and operando (X-Ray diffraction) technics performed at SOLEIL (France) and SPring-8 (Japan) synchrotron facilities. Finally, devices coupling BSCF based positive electrode material with activated carbon or FeWO4 based negative electrode materials have demonstrated the added value of such materials to improve the volumetric energy density of supercapacitors

Oxydes polycationiques pour supercondensateurs à haute densité d'énergie volumique

Supercapacitors are attractive electrochemical energy storage devices for high power applications. However, volumetric energy density is the main limitation for their integration in such applications as terrestrial transport systems. The use of high density pseudocapacitive oxides as electrode material could lead to a volumetric energy density improvement. With this aim, materials from Ba0,5Sr0,5CoxFe1-xO3-δ family, so called BSCFs, have been studied. Several compositions have been prepared and evaluated as positive electrode materials in aqueous neutral electrolyte. Volumetric capacitances have shown to be greater than those of activated carbons, already used in marketed supercapacitors. They have also shown to depend on cobalt and iron ratio, charge rate, electrolyte composition... The study of the charge storage mechanism in these materials has been investigated thanks to in situ (X-Ray absroption spectroscopy) and operando (X-Ray diffraction) technics performed at SOLEIL (France) and SPring-8 (Japan) synchrotron facilities. Finally, devices coupling BSCF based positive electrode material with activated carbon or FeWO4 based negative electrode materials have demonstrated the added value of such materials to improve the volumetric energy density of supercapacitors.Les supercondensateurs sont des dispositifs de stockage électrochimique de l’énergie très intéressants lorsque des pics de puissance sont mis en jeu. Toutefois, leur densité d’énergie volumique est la principale limite pour leur intégration, en particulier, dans des systèmes de transport terrestre. L’utilisation de matériaux d’électrode ayant un comportement pseudocapacitif et des masses volumiques élevées permettrait d’améliorer la densité d’énergie volumique des supercondensateurs. Avec cet objectif, des dispositifs à base des matériaux de la famille Ba0,5Sr0,5CoxFe1-xO3-δ, nommés BSCFs, ont été développés dans le cadre de cette thèse. Plusieurs compositions de cette famille d’oxydes ont été préparées par un procédé glycine-nitrate et ont été testés comme matériau actif d’électrode positive en milieu aqueux neutre. La capacité volumique de ces matériaux s’avère être beaucoup plus élevée que celle des carbones activés utilisés dans les supercondensateurs commerciaux. Elle a montré également dépendre de la composition en cobalt et en fer, du régime de charge, de la nature de l’électrolyte… Le mécanisme de stockage de charges dans ces matériaux a été exploré grâce à des techniques in situ (absorption des rayons X) et operando (diffraction des rayons X) effectuées aux synchrotrons SOLEIL (France) et SPring-8 (Japon). Enfin, des dispositifs associant une électrode positive à base de BSCF et du carbone activé ou FeWO4 en tant qu’électrode négative ont démontré l’intérêt d’intégrer de tels matériaux pour améliorer la densité d’énergie volumique des supercondensateurs

Etude sur la gangrène infectieuse disséminée de la peau

Thèse : Médecine : Université de Bordeaux : 1905N° d'ordre : 9

Electrochemical study of asymmetric aqueous supercapacitors based on high density oxides: C/Ba0.5Sr0.5Co0.8Fe0.2O3-δ and FeWO4/Ba0.5Sr0.5Co0.8Fe0.2O3-δ

International audienceTwo asymmetric aqueous electrochemical capacitors operated in 5 M LiNO3 are reported: C/Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and FeWO4/BSCF, with activated carbon and FeWO4 (synthesized by a precipitation method) as negative electrodes, respectively, and BSCF (synthesized by a modified glycine-nitrate process) as positive electrodes. These two devices were operated between 0 and 1.6 V and between 0 and 1.4 V, respectively. They demonstrated a remarkable cycling ability with a high capacitance retention over 10,000 and 45,000 cycles, respectively. Thanks to the high density of BSCF, the C/BSCF device exhibits a volumetric energy density up to 2.7 Wh L−1 at low current densities. This study demonstrates the advantages and limits of the use of high density multicationic oxides with pseudocapacitive behavior to improve the volumetric energy density of aqueous electrochemical capacitors

Investigation of Ba 0.5 Sr 0.5 Co x Fe 1-x O 3-δ as a pseudocapacitive electrode material with high volumetric capacitance

International audienceBa0.5Sr0.5CoxFe1-xO3-d phases, with 0.75 < x < 0.90, so-called BSCFs, were investigated as pseudocapacitive electrode materials. These polycationic oxide phases were prepared by a modified glycine-nitrate process and show the same perovskite structural arrangement and similar morphological characteristics in the whole series. The electrochemical performance was evaluated in aqueous electrolytes at room temperature. BSCF powders showed promising pseudocapacitive behavior as electrode materials with high volumetric capacitances which depend on the Co/Fe ratio. A volumetric capacitance of 500 F cm-3 , i.e. five times higher than that of a standard activated carbon electrode, was measured in 5.0 M LiNO3 for the electrode based on Ba0.5Sr0.5Co0.8Fe0.2O3-d material composition (x = 0.80). The electrode also exhibited moderate self-discharge and 90% of capacitance retention over 2000 cycles. The charge storage mechanism seems to be dependent upon the nature of the ions in the electrolyte and on the Co/Fe ratio

“Water-in-Salt” for Supercapacitors: A Compromise between Voltage, Power Density, Energy Density and Stability

International audienc

Polycationic oxides as potential electrode materials for aqueous-based electrochemical capacitors

International audienc

Exploring complementarity of Life Cycle Thinking and Landscape & Urban Planning towards sustainable urban co-design.: Case study : Electric based tricycle technologies for last kilometer delivery

International audienceNowadays, sustainability is gaining importance in territorial policies. Yet, no substantial efforts have been deployed for systematically integrating environmental, social and economic aspects in early stages of urban service co-design. While Life Cycle Assessment (LCA) is a suitable method for impact assessment of products and services, Landscape-Urban Planning (LUP) provides information on how these products and services interact at the territorial scale. Our understanding of urban systems’ needs could go a step further towards better consumption patterns and resources optimization by coupling both approaches. This work explores the synergy between Life Cycle Thinking and Landscape-Urban Planning by their application to an essential urban service: logistics. The challenging metabolism of high-density urban systems is taken as an opportunity to consider emergent logistic solutions, specifically electric tricycle technologies for last kilometer delivery. Firstly, we start by applying each approach individually; following LUP perspective, we define a territorial reading grid, based on a set of criteria describing physical, socio-cultural, and economic resources of a landscape. Then, using LCA, we quantify potential impacts or benefits of electric tricycles technology compared to the existing delivery technologies. Electricity for tricycle batteries’ charging is provided by photovoltaic systems. In a second step, results from both approaches are coupled to determine local urban hotspots that describe the main aspects to meet stakeholders’ needs and improve their living conditions. Sustainability design parameters are, thus, defined to optimize the tricycle technology. Finally, the design and optimization of the electric tricycle-based delivery system is carried out. The Geographical Information System (i.e .Quantum GIS) is used to explore local data on solar energy potential spots, cycling infrastructures, potential urban logistic platforms, etc. Energy required has been computed to determine adequate charging infrastructures, taking topography and climate conditions into account. Intelligent logistic planning is performed to improve efficiency, optimize the streamline to reduce environmental impacts and simulate interaction with other urban transportation flows. Based on the current case study, the urban service co-design framework has been fully established in order to gain sustainability in a territorial management scale through LCA and LUP perspectives