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Morales M.,University of Barcelona | Morales M.,Diopma Inc. | Roa J.J.,Polytechnic University of Catalonia | Tartaj J.,CSIC - Institute of Ceramics and Glass | Segarra M.,University of Barcelona
Journal of the European Ceramic Society | Year: 2016

The present review is focused on SrO- and MgO-doped lanthanum gallates (LSGMs), specifically in those key aspects related to their implementation as electrolyte for Intermediate Temperature Solid Oxide Fuel Cells. After a brief survey of the state-of-the-art for the LSGMs, the attention is focused on the ionic transport properties for the relevant compositions. The design, manufacturing and performance of cells using LSGM as electrolyte are discussed along the review. Particular interest is given to the impact of synthesis routes for lowering their sintering temperatures. A short discussion on the chemical compatibility between electrolyte and electrodes in cells is also included. Afterwards, mechanical and thermal properties of LSGMs reported determined though conventional methods at different working temperatures are discussed. Finally, the microstructural and compositional effects related to their electrical and mechanical properties at micro- and nanometric length scale are assessed as a complementary tool for future developments in solid electrolyte materials. © 2015 Elsevier Ltd. Source


Morales M.,University of Barcelona | Morales M.,Diopma Inc. | Laguna-Bercero M.A.,University of Zaragoza | Navarro M.E.,University of Birmingham | And 2 more authors.
RSC Advances | Year: 2015

Different cell configurations of anode-supported microtubular solid oxide fuel cells (mT-SOFCs) using samaria-doped ceria (SDC) as the electrolyte were fabricated. Several cells were processed varying the porosity and wall thickness (outer diameter) of NiO-SDC tubular supports. Suitable aqueous slurry formulations of NiO-SDC for gel-casting were prepared using agarose, as a gelling agent, and sucrose, as a pore former. The subsequent NiO-SDC anode functional layer (AFL), the SDC electrolyte and the La0.6Sr0.4Co0.2Fe0.8O3-δ-SDC cathode were deposited by spray-coating. Pre-sintering temperatures of the supports were optimized from linear shrinkage curves, thus obtaining after co-sintering, a dense electrolyte without anode-electrolyte delamination. Electrochemical characterization of mT-SOFC cells fabricated by agarose gel-casting is reported by the first time. The cell with a support of 2.6 mm diameter, 380 μm wall thickness, an active area of 1 cm2 and added porosity, using 10 wt% sucrose, achieved a maximum power density of about 400 mW cm-2 at 650°C. © The Royal Society of Chemistry 2015. Source


Morales M.,University of Barcelona | Morales M.,Diopma Inc. | Espiell F.,University of Barcelona | Segarra M.,University of Barcelona
Journal of Power Sources | Year: 2015

Anode-supported single-chamber solid oxide fuel cells with and without Cu-ZnO-Al2O3 catalyst layers deposited on the anode support have been operated on ethanol and air mixtures. The cells consist of gadolinia-doped ceria electrolyte, Ni-doped ceria anode, and La0.6Sr0.4CoO3-δ-doped ceria cathode. Catalyst layers with different Cu-ZnO-Al2O3 ratios are deposited and sintered at several temperatures. Since the performance of single-chamber fuel cells strongly depends on catalytic properties of electrodes for partial oxidation of ethanol, the cells are electrochemically characterized as a function of the temperature, ethanol-air molar ratio and gas flow rate. In addition, catalytic activities of supported anode, catalytic layer-supported anode and cathode for partial oxidation of ethanol are analysed. Afterwards, the effect of composition and sintering temperature of catalyst layer on the cell performance are determined. The results indicate that the cell performance can be significantly enhanced using catalyst layers of 30:35:35 and 40:30:30 wt.% Cu-ZnO-Al2O3 sintered at 1100°C, achieving power densities above 50 mW cm-2 under 0.45 ethanol-air ratio at temperatures as low as 450°C. After testing for 15 h, all cells present a gradual loss of power density, without carbon deposition, which is mainly attributed to the partial re-oxidation of Ni at the anode. © 2015, Elsevier B.V. All rights reserved. Source


Ruiz-Morales J.C.,University of La Laguna | Marrero-Lopez D.,University of Malaga | Pena-Martinez J.,University of Castilla - La Mancha | Canales-Vazquez J.,University of Castilla - La Mancha | And 4 more authors.
Journal of Power Sources | Year: 2010

A novel design, alternative to the conventional electrolyte-supported solid oxide fuel cell (SOFC) is presented. In this new design, a honeycomb-electrolyte is fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. This new design allows a reduction of ∼70% of the electrolyte material and it renders modest performances over 320 mW cm-2 but high volumetric power densities, i.e. 1.22 W cm-3 under pure CH4 at 900 °C, with a high OCV of 1.13 V, using the standard Ni-YSZ cermet as anode, Pt as cathode material and air as the oxidant gas. © 2009 Elsevier B.V. All rights reserved. Source


Segarra M.,University of Barcelona | Espiell F.,University of Barcelona | Morales M.,University of Barcelona | Morales M.,Diopma Inc.
Materials Today: Proceedings | Year: 2015

Fuel Cells (FCs) are electrochemical devices that directly convert the chemical energy of a reaction into electrical energy. The energy conversion processes theoretically remain unaltered as long as the fuel and oxidant feed the device. A single cell consists of two electrodes (anode and cathode), and an electrolyte, which can be a solid oxide that transports ions, thus becoming a SOFC (solid oxide fuel cell). To achieve the oxide-ion conductivity necessary to ensure high enough power density, these fuel cells require high and/or intermediate temperatures (over 500. °C).The fuel conversion efficiency of conventional SOFCs is usually about 50%. Thus, much of the chemical energy converts into waste heat energy, whereas thermoelectric materials can generate electricity from the waste heat. Some studies have been published in which the cathode of the fuel cell has been replaced by a thermoelectric material, and different simulation studies have been performed in which the waste heat is harnessed by thermoelectrics in a heat exchanger. The aim of this work is to provide an overview of thermoelectric materials that could help to select the best one to harness the heat evolved by a SOFC device to increase its efficiency. Data has been collected for different thermoelectric materials, including their thermoelectric performance, operation temperature range, and cost. To choose a thermoelectric material, it is necessary to define a performance parameter that allows us to classify all the different materials by means of their performance. Among the best, operating temperature and cost will turn into constraints that must be met to find the best material that suits the characteristics of a SOFC operation environment, and that really can be used in combination with the fuel cell. © 2015. Source

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