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TECHNICAL BRIEFS

# Reduction and Reoxidation Processes of $NiO∕YSZ$ Composite for Solid Oxide Fuel Cell Anodes

[+] Author and Article Information
Stefano Modena, Sergio Ceschini, Andrea Tomasi

ITC-Irst, Center for Scientific and Technological Research, v. Sommarive, 18 – 38050 Povo (TN), Italy

Dario Montinaro, Vincenzo M. Sglavo

Department of Materials Engineering and Industrial Technologies, University of Trento, v. Mesiano, 77 – 38050 Trento, Italy

J. Fuel Cell Sci. Technol 3(4), 487-491 (Mar 17, 2006) (5 pages) doi:10.1115/1.2349533 History: Received November 30, 2005; Revised March 17, 2006

## Abstract

Solid oxide fuel cells (SOFCs) are an emerging technology in hydrogen-based energy production, thanks to their high performance, high power density, high efficiency, and reduced emissions over conventional power generation technologies. For these reasons, a great attention has been addressed in these years to SOFCs materials and technologies. An important issue related to the utilization of SOFCs as power generators is the capability of SOFCs materials to resist to thermal cycles in different atmospheres. The present work proposes an experimental investigation on the reduction process of $NiO∕YSZ$ anode into $Ni∕YSZ$ cermet, which is the best candidate for anode material in SOFCs, its reoxidation into $NiO∕YSZ$ and the following rereduction into $Ni∕YSZ$. Anodes with different $NiO∕YSZ$ ratios were analyzed through different physical and chemical techniques, such as scanning electron microscopy (SEM) and porosity measurements. The reduction, reoxidation and rereduction behaviors were studied by thermogravimetric analysis (TGA) in a unique long experiment, at different temperatures in the range of 700–$800°C$. The kinetics of the processes was studied and thermodynamic parameters such as activation energy were also calculated and correlated to the compositions and microstructure of the materials. The study clears up the effect of anode composition and microstructure on the reduction, reoxidation, and rereduction processes.

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## Figures

Figure 5

Normalized mass change versus time upon rereduction for sample A (a) and sample B (b)

Figure 1

SEM image of the typical microstructure after reduction of an anode supported SOFC

Figure 2

Normalized mass change versus time upon reduction for sample A (a) and sample B (b)

Figure 3

SEM images of the anode microstructure for sample A: (a) as prepared, (b) after reduction at 700°C; and (c) after reduction at 800°C

Figure 4

Normalized mass change versus logarithmic time upon oxidation for sample A (a) and sample B (b)

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