Cromitas de Lantano como potencial electrodos simétricos para Pilas de Combustible de Óxido Sólido

Abstract

A commonly used interconnector material has been tested as electrode for a new concept of Solid Oxide Fuel Cell, where the same material could be used, simultaneously, as interconnector, anode and cathode. We have found that a typical substituted chromite, such as La 0.7 Ca 0.3 CrO 3-δ (LCC) can be considered a good candidate for such configuration, due to its high electronic conductivity in both reducing and oxidising conditions, and moderate catalytic properties for oxygen reduction and hydrogen oxidation. The symmetrical design renders performances of 100 mWcm -2 at 950ºC, using O 2 and H 2 as oxidant and fuel respectively. Performances exceeding 300 mWcm -2 can be predicted for a 100µm-thick YSZ electrolyte. Keywords: Solid Oxide Fuel Cell, symmetrical electrodes, interconnector, YSZ, Chromites Cromitas de Lantano como potencial electrodos simétricos para Pilas de Combustible de Óxido SólidoUn material comúnmente utilizado como interconector ha sido probado como electrodo para un nuevo concepto de Pila de Combustible de Óxidos Sólido, en el cual el mismo material se utiliza, simultáneamente, como interconector, ánodo y cátodo. Hemos encontrado que una cromita típica como La 0.7 Ca 0.3 CrO 3-δ (LCC) puede ser considerada una buena candidata para dicha configuración, debido a sus altas conductividades eléctricas tanto en condiciones reductoras como oxidantes y una aceptable actividad catalítica para la reducción del oxígeno y la oxidación del hidrógeno. El diseño simétrico permite obtener rendimientos del orden de 100mWcm -2 a 950ºC, utilizando O 2 e H 2 como oxidante y combustible, respectivamente. Rendimientos que superan los 300mWcm -2 pueden predecirse para pilas con electrolitos de YSZ de 100 µm de grosor.

Progress and Prospects in Symmetrical Solid Oxide Fuel Cells with Two Identical Electrodes

“…LSCM+YSZ (1:1 in weight ratio) composite was used as the electrode of a symmetrical cell, which was further impregnated with GDC0.2 at a loading content of 0.4 mg cm −2 to improve the electrode activity for ORR and fuel oxidation. The power outputs were signifi cantly improved compared with those of a cell with a pure LCC electrode as previously reported by Ruiz-Morales et al [ 75 ] Such improvement can be explained by the increased oxygenion conductivity after the introduction of the GDC0.2 phase to the electrode, and the LSGM electrolyte also likely contributed to the improved performance by decreasing the ohmic resistance of the cell electrolyte. An LSCM+YSZ cathode-supported SOFC with a thin-fi lm YSZ electrolyte (≈50 µm) and an LSCM+YSZ anode was fabricated, which delivered PPDs of 275 and 162 mW cm −2 at temperatures of 850 and 700 °C, respectively.…”

“…The cell operation was relatively stable at 850 °C for a period of 20 h even on city gas. The power outputs were significantly improved compared with those of a cell with a pure LCC electrode as previously reported by Ruiz‐Morales et al Such improvement can be explained by the increased oxygen‐ion conductivity after the introduction of the GDC0.2 phase to the electrode, and the LSGM electrolyte also likely contributed to the improved performance by decreasing the ohmic resistance of the cell electrolyte. Lin et al also tested the performance of a symmetrical SOFC with LCC97+YSZ (1:1) composite as its electrodes and 350 μm thick YSZ as the electrolyte.…”

“…[ 75 ] A modest level of power output with a peak power density (PPD) of 110 mW cm −2 was achieved at 950 °C for a 200 µm-thick yttria-stabilized zirconia (YSZ) electrolytesupported symmetrical cell with La 0.7 Ca 0.3 CrO 3 (LCC) electrodes operating on humidifi ed hydrogen fuel. Recently, A-site doped LaCrO 3 perovskite oxides have been exploited as electrode materials of symmetrical SOFCs.…”

“…In the context of chemical stability, doped Ln CrO 3 ‐based oxides ( Ln = La, Pr), the state‐of‐the‐art materials used as the interconnector in high‐temperature SOFCs, may be the most representative perovskite oxide known, showing high stability and affordable electrical conductivity under both oxidizing and reducing atmospheres. Recently, A‐site doped LaCrO 3 perovskite oxides have been exploited as electrode materials of symmetrical SOFCs . A modest level of power output with a peak power density (PPD) of 110 mW cm −2 was achieved at 950 °C for a 200 μm‐thick yttria‐stabilized zirconia (YSZ) electrolyte‐supported symmetrical cell with La 0.7 Ca 0.3 CrO 3 (LCC) electrodes operating on humidified hydrogen fuel.…”

Redox Stable Anodes for Solid Oxide Fuel Cells

“…As potential SOFC anode materials, suitable ceramic candidates need to meet the following requirements (Goodenough and Huang, 2007;Fu and Tietz, 2008;Ruiz-Morales et al, 2011). (1) Electronic conductivity.…”