High-Temperature Radiative Behavior of an La2NiO4+δ Cathodic Layer for SOFCs (up to 900°C): Influence of δ and Texture

Abstract

Thermal radiation is likely to play an important role in the calculation of the energy balance in solid oxide fuel cells (SOFCs), due to their high operating temperatures (600°–1000°C). However, the majority of previous studies dealing with this issue have used room-temperature radiative data for determining the overall heat transfer process within a given cell, which could lead to an inexact appreciation of the role played by the thermal radiation. Consequently, the thermal field within the cell could also be incorrectly determined; however, accurate knowledge of the thermal field is important in order to understand the mechanical behavior of SOFCs. Several parameters, including chemical composition, texture, thickness, and of course operating temperature, have a large effect on the radiative properties of a given compound. As a first step to elucidate the temperature-dependent behavior of SOFCs, we deposited an La2NiO4+δ cathodic layer on a planar ZrO2–8% Y2O3 electrolyte-supported SOFC and investigated its radiative properties using high-temperature infrared emissivity spectroscopy (100°–900°C). Additional X-ray diffraction, thermo-gravimetric analysis, and environmental scanning electron microscopy measurements were also made to study the role played by both the chemical composition and texture on the radiative properties of the cell.