LiMn2-xGexO4 como material catódico para baterías de ión-litio

32 p.[Spa] En el trabajo presentado a continuación se ha llevado a cabo las síntesis del compuesto LiMn2-xGexO4 (x=0; 0.05; 0.1; 0.15; 0.2) vía liofilización. Mediante este proceso de síntesis se ha conseguido reducir a escala nanométrica el tamaño de grano de las fases electroactivas. La caracterización de las muestras realizadas se ha llevado a cabo mediante difracción de rayos X sobre muestra policristalina, microscopia electrónica de transmisión (TEM), resonancia paramagnética electrónica (RPE) o resonancia de espín electrónico (REE) y estudio electroquímico mediante celdas Swagelok. La sustitución catiónica de Mn4+ por una pequeña cantidad de Ge4+, tiene como objeto estabilizar la estructura de la espinela para paliar el efecto Jahn-Teller sin reducir la cantidad del catión electroactivo Mn3+.[Eng] In the work presented below was carried out the synthesis of the compound LiMn2-xGexO4 (x=0; 0.05; 0.1; 0.15; 0.2) by freeze-drying method. Through this process of synthesis the grain size has been reduced to the nanometric scale successfully. Sample characterization has been performed by X-ray powder diffraction, transmission electronic microscopy (TEM), electron paramagnetic resonance (EPR) or electron spin resonance (ESR) and electrochemical test with Swagelok cells. The cationic substitution of a small amount of Mn4+ by Ge4+, aims to stabilize the structure of the spinel to alleviate the Jahn-Teller effect without reducing the amount electroactive cation Mn3+.Ayuda económica de BCMaterial

Optimization of the large scale synthesis of the LSF-20 cathode material for SOFCs

Póster presentado en: 21st World Hydrogen Energy Conference 2016. Zaragoza, Spain. 13-16th June, 2016Solid oxide fuel cells (SOFCs) have the potential to be one of the cleanest and most efficient energy technologies for direct conversion of chemical fuels to electricity. Economically competitive SOFC systems appear poised for commercialization, but widespread market penetration will require continuous innovation of materials and fabrication processes to enhance system lifetime and reduce cost. Additional requirements arise for the technologies for synthesis of SOFC materials. These requirements originate from the demands for large scale SOFC industrial production. In this sense, solution combustion synthesis (SCS) is a simple and reproducible method used to obtain several types of ceramic oxides for a variety of applications. A typical SCS procedure utilizes a self-sustained exothermic reaction among well-mixed reactants to achieve the rapid and economical synthesis of particulate products. Up to 2008, SCS method has been adopted to fabricate more than 1000 kinds of oxide powders over more than 65 countries [1]. The properties of the resulting powders (crystalline structure, amorphous structure, crystallite size, purity, specific surface area and particle agglomeration) depend heavily on the adopted processing parameters [2,3]. The objective of this work is to obtain, on a large scale, the perovskite-type oxide La0.8Sr0.2FeO3 that shows promising properties as cathode for SOFC applications. In this study, the optimization of the large scale synthesis has been realized by the glycine-nitrate combustion method (Figure 1). In this sense, first of all, the effect of some parameters such as temperature, glycine/nitrate ratio and times and cooling rates used in the temperature treatments, that play a key role in the final properties of the obtained materials, has been analyzed. The characterization has been realized by ICP (inductively coupled plasma atomic emission spectroscopy) XRD (X Ray diffraction), SEM (scanning electron microscopy) and dilatometry.This research has been funded by the Ministerio de Economía y Competitividad (MAT2013-42092-R) with co-financing FEDER-EU) and Dpto. Educación, Política Lingüística y Cultura of the Basque Goverment (IT-630-13). The authors thank SGIker (UPV/EHU) technical support

SOFC development at CNH2

Abstract del 4th International Symposium on the Catalysis for Clean Energy and Sustainable Chemistry. Bilbao, Spain July 9-11 (2018).Solid oxide fuel cells (SOFC´s) are devices that convert chemical energy from reactants into heat and electricity with high efficiency. Usually, these systems operate at high temperatures (600-1000ºC) and are able to run with different fuels. Here we present the current activities that are being carried out at the Solid Oxide laboratory of the Hydrogen National Centre in Spain, which is focused on the development and electrochemical characterization of SOFC materials and devices

SOFC development at CNH2

Abstract del 4th International Symposium on the Catalysis for Clean Energy and Sustainable Chemistry. Bilbao, Spain July 9-11 (2018).Solid oxide fuel cells (SOFC´s) are devices that convert chemical energy from reactants into heat and electricity with high efficiency. Usually, these systems operate at high temperatures (600-1000ºC) and are able to run with different fuels. Here we present the current activities that are being carried out at the Solid Oxide laboratory of the Hydrogen National Centre in Spain, which is focused on the development and electrochemical characterization of SOFC materials and devices

Scalable synthetic method for SOFC compounds

Although economically competitive SOFC systems seems to be ready for commercialization, a broad inventory of key starting materials and fabrication processes are needed to enhance systems and reduce costs. These necessities are raised by the demands for large scale SOFC industrial production. Taking into account these reasons, we have synthesized the mean components of a fuel cell, on a large scale, by the glycine nitrate combustion method. The synthesized different components of SOFC have been the interconnector protective coating (MnCo1.9Fe0.1O4), contact layer (LaNi0.6Fe0.4O3), cathode (La0.6Sr0.4FeO3), interlayer (Sm0.2Ce0.8O1.9), electrolyte (ZrO2)0.92(Y2O3)0.08 and anode (Ni0.3O-(ZrO2)0.92(Y2O3)0.08) material, obtaining reproducible pure samples and amounts up to 12 g for each batch, being able to increase easily this amount to lots of hundred of grams. The obtained materials have been characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and X-ray fluorescence (XRF), X-ray diffraction (XRD), dilatometry, scanning electron microscopy (SEM), particle size distribution and conductivity measurements.Ministerio de Economía, Industria y Competitividad (MAT2016-76739-R) (AEI/FEDER, UE) and (MAT2015-2015-86078-R) Dpto. Educación del Gobierno Vasco (IT-630-13) European Regional Development Fund (ERDF). Ministerio de Economía y Competitividad (BES-2014-068433

Synthesis of new Ln₄(Al₂O₆F₂)O₂ (Ln = Sm, Eu, Gd) phases with a cuspidine-related structure

The first fluorination of the cuspidine-related phases of Ln4(Al2O7□)O2 (where Ln = Sm, Eu, Gd) is reported. A low-temperature reaction with poly(vinyl-idene difluoride) lead to the fluorine being substituted in place of oxygen and inserted into the vacant position between the dialuminate groups. X-ray photoelectron spectroscopy shows the presence of the F 1s photoelectron together with an increase in Al 2p and rare-earth 4d binding energies supporting F incorporation. Energy-dispersive X-ray spectroscopy analyses are consistent with the formula Ln4(Al2O6F2)O2, confirming that substitution of one oxygen by two fluoride atoms has been achieved. Rietveld refinements show an expansion in the cell upon fluorination and confirm that the incorporation of fluoride in the Ln4(Al2O7□)O2 structure results in changes in Al coordination from four to five. Thus, the isolated tetrahedral dialuminate Al2O7 groups are converted to chains of distorted square-based pyramids. These structural results are also discussed based on Raman spectra.This research was funded by the Ministerio de Economía, Industria y Competitividad (MAT2016-76739-R) (AEI/FEDER, UE), and Departamento de Educación of the Basque Government (IT-630–13). The authors thank SGIker of UPV/EHU for technical and personnel support. A. Mora´nRuiz thanks UPV/EHU for funding.Peer reviewe

Negative correlation of doping and conductivity in Ln1-xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x≤0.25) perovskites prepared by combustion synthesis as anode materials for SOFCs

A series of chromite perovskites with the general formula Ln1−xMxCr0.9Ni0.1O3 (Ln = La and/or Nd; M = Sr and/or Ca; x ≤ 0.25) has been prepared by three combustion synthesis routes using a different combustible substance each time: glycine, urea and sucrose. In order to isolate the effect of divalent dopant concentration from the A cation steric effects, the whole group has a fixed mean A cation radius, ≈ 1.22 Å, and cation size disorder, σ2(rA) ≈ 0.0001 Å2, but variable doping x. Their crystal structure, microstructure, electrical properties and expansion coefficients have been investigated on the basis of their possible use as anode materials for intermediate temperature solid oxide fuel cells (SOFC). Cell parameters, grain sizes, expansion coefficients and conductivities all are found to be dependent on x and the combustible substance used. The most interesting relationship is the negative dependence of the conductivity with x under H2 atmosphere: conductivity decreases with doping which is the opposite to the expected behavior for a p-type doped perovskites and has not been reported before.Ministerio de Economía y Competitividad, MAT2016-76739-R // Dpto. Educación, Política Lingüística y Cultura of the Basque Government, IT-630-1

Celdas de pilas de oxidó solido, avance en el procesado de materiales

Póster presentado en el XIV Congreso Nacional de Materiales (CNMAT) en Gijón (España), del 8 al 10 de Junio de 2016Este trabajo está enfocado a la síntesis y al procesado de los componentes de las pilas de combustible de óxido sólido (SOFC). La configuración empleada consiste en celdas (ánodo/electrolito/cátodo) soportadas por el electrolito. Se han sintetizado los compuestos, NiO-(ZrO2)0.92(Y2O3)0.08, (ZrO2)0.92(Y2O3)0.08 y La0.6Sr0.4FeO3 como ánodo, electrolito y cátodo, respectivamente. Con objeto de disminuir la reactividad electrolito-cátodo, se ha empleado una barrera Ce0.8Sm0.2O1.9 entre ambos componentes. En buen acuerdo con K. Vidal y col. 1 se ha utilizado la técnica de combustión por glicina-nitrato para la síntesis de los compuestos. La evaluación de la pureza, morfología y conductividad se ha llevado a cabo mediante difracción de rayos X (XRD) (método Rietveld), microscopía electrónica de barrido (MEB) y medidas de conductividad en bulk a través del método de cuatro puntos. Para el procesado del electrolito se ha empleado una prensa hidráulica, obteniéndose pastillas de 20 mm de diámetro y 500μm de espesor. Éstas se han sinterizado a 1450 ºC durante 4 h en aire, con objeto de alcanzar las propiedades físico-químicas adecuadas. La deposición del ánodo, cátodo y barrera se ha realizado por spray manual coloidal, empleándose una solución en base orgánica. Para analizar el comportamiento electroquímico de la estructura multicapa, se han realizado medidas de impedancia a 800 ºC durante 100 h. La degradación de los sistemas se ha estudiado a partir de análisis por energía dispersiva de rayos X (EDX) mediante el análisis de las micrografías de las secciones transversales. Agradecimientos: Esta investigación haEsta investigación ha sido financiada por el Dpto. Educación, Política Lingüística y Cultura del Gobierno Vasco (IT-630-13) y al Ministerio de Economía y Competitividad (MAT2013-42092-R). Ministerio de Economía y Competitividad por la beca (BES-2014-068433)

Design and development of solid oxide fuels cells.

260 p.En este trabajo se ha recogido el diseño y desarrollo del procesado de pilas SOFC, partiendo desde la síntesis de grandes cantidades de material de partida y finalizando con la fabricación y caracterización de celdas en funcionamiento, lo que ha permitido la identificación y adaptación de las propiedades clave para obtener este tipo de celdas.Estos prototipos acercarán a la sociedad la comercialización de los sistemas de generación de energía sostenible