Quantitative Comparison of Different Approaches for Reconstructing the Carbon-Binder Domain from Tomographic Image Data of Cathodes in Lithium-Ion Batteries and Its Influence on Electrochemical Properties

It is well known that the spatial distribution of the carbon binder domain CBD offers a large potential to further optimize lithium ion batteries. However, it is challenging to reconstruct the CBD from tomographic image data obtained by synchrotron tomography. Herein, several approaches are considered to segment 3D image data of two different cathodes into three phases, namely, active material, CBD, and pores. More precisely, it is focused on global thresholding, a local closing approach based on energy dispersive X ray spectroscopy data, a k means clustering method, and a procedure based on a neural network that has been trained by correlative microscopy, i.e., based on data gained by synchrotron tomography and focused ion beam scanning electron microscopy data representing the same electrode. The impact of the considered segmentation approaches on morphological characteristics as well as on the resulting performance by spatially resolved transport simulations is quantified. Furthermore, experimentally determined electrochemical properties are used to identify an appropriate range for the effective transport parameter of the CBD. The developed methodology is applied to two differently manufactured cathodes, namely, an ultrathick unstructured cathode and a two layer cathode with varying CBD content in both layers. This comparison elucidates the impact of a specific structuring concept on the 3D microstructure of cathode

Der Einfluss der Adsorption auf die Sauerstoffreduktionsreaktion : perfluoralkylierte Phosphorsäurederivate als Modellverbindungen zur Untersuchung der Anionenadsorption an Platin

In this work, the influence of anion-adsorption on the oxygen reduction reaction (ORR) at platinum electrocatalysts is evaluated. By chemical modification of the electrolyte composition, polarization-losses for the ORR shall be reduced in order to enhance power-densities in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). This was studied systematically for the first time by substitution of hydroxyl groups in phosphoric acid by perfluorinated alkyl chains. Perfluoro-alkylated phosphonic- and phosphinic acids proved to be both electro-chemically and thermally stable enough to serve as potential HT-PEMFC electrolytes. Compared with H3PO4 (PA), these acids exhibit substantially weaker adsorption tendencies on the surface of a platinum-based electrocatalyst. Consequently, overpotentials for the ORR on a flat platinum surface are reduced by 75%. The number of hydroxyl groups within the acid molecules and the negative charge density of their corresponding anions were identified as the main descriptor for their adsorption behavior, whereas the length of the perfluorinated side chain did not affect the ORR kinetics negatively. The activation barrier for the ORR on a flat platinum surface was reduced by 40% by adding bis(pentafluoroethyl)-phosphinic acid (BPPA) to the host electrolyte instead of PA. Under the same experimental conditions, the charge transfer resistance for the ORR decreased by more than three orders of magnitude. Electro-catalytic activities for the ORR at Pt3Co/C- and Pt/C-electrocatalysts were found to be significantly higher in perfluorinated electrolytes than in PA. In the pres-ence of BPPA, an enhancement of 85% was achieved. After accelerated aging proce-dures, the electro-chemical active surface area (ECA) decreased significantly. However, electro-catalytic activities for the ORR were still three orders of magnitude higher compared with PA under the same experimental conditions. The ORR-selectivity at Pt3Co/C- and Pt/C was measured to be dependent on the nature of the adsorbed species. The rate of peroxide production was correlated with the steric demand of the anionic species, with larger anions yielding more hydrogen peroxide. A HT-PEMFC single cell setup was successfully operated with mixtures of PA and 20% perfluoroalkyl-substituted phosphonic acids. Compared to operation with PA as an electrolyte, the performance was enhanced significantly

Características estratigráficas y fosilíferas del Neógeno en el oeste de San Luis. Argentina

Se describen los depósitos neógenos del piedemonte suroriental de la Cerrillada de las Cabras en el Cordón de Serranías Occidentales en la provincia de San Luis. Los mismos están identificados como Formación Las Mulitas y en base al registro fósil se asignan al Mioceno medio-Plioceno inferior. El objetivo de esta contribución es la mención del primer registro fósil en el área del Perfil El Cráter (33°18´14,35´´S, 66°54´3,12´´O) correspondiente a 23 metros de una interestratificación de areniscas, limolitas y conglomerados consolidados, macizos y de estructuras plano-paralela, laminar y entrecruzada de bajo ángulo, geometría tabular dominante y aislados cuerpos lenticulares, canalizados, con cemento calcáreo y yeso, contactos netos e incipientemente erosivos, planos a levemente ondulosos, el color varía de pardo amarillento a pardo rojizo. En la sección media del perfil, en areniscas con estratificación horizontal, geometría tabular y abundante cemento calcáreo, laminar y nodular, además de yeso laminar y en rosetas, representando un ambiente fluvial de energía moderada a relativamente alta se descubrió un hueso indeterminado de gran tamaño, incompleto y aislado. El fósil exhibe fracturación, agrietamiento, descamación y abrasión vinculadas al transporte hidráulico. Las secciones delgadas muestran hueso compacto con abundantes osteonas secundarias indicando alto grado de remodelación ósea. Estas estructuras están formadas por lamelas concéntricas de hueso endosteal con lagunas de osteocitos y líneas de cementación bien definidas. Las osteonas presentan los canales centrales (de Havers) y los canales oblicuos o transversales (de Volkmann), así como las grietas y fracturas rellenas con óxidos de hierro y calcita.Fil: Chiesa, Jorge Orlando. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; ArgentinaFil: Basaez, Alberto Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; ArgentinaFil: Pizarro, Lautaro Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; ArgentinaFil: Ojeda, Guillermo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Universidad Nacional de San Luis; ArgentinaFil: Heider, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Previtera, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina1ra Reunión Virtual de Comunicaciones de la Asociación Paleontológica ArgentinaCiudad Autónoma de Buenos AiresArgentinaAsociación Paleontológica Argentin