Densification behavior of yttria-stabilized zirconia powders for solid oxide fuel cell electrolytes

Dhruba Panthi,Yanhai Du,Nader Hedayat

doi:10.1007/s40145-018-0282-4

Abstract

Yttria-stabilized zirconia (YSZ) is the most common electrolyte material for solid oxide fuel cells. Herein, we conducted a comparative study on the densification behavior of three different kinds of commercial 8 mol% YSZ powders: (i) TZ-8Y (Tosoh, Japan), (ii) MELox 8Y (MEL Chemicals, UK), and (iii) YSZ-HT (Huatsing Power, China). The comparison was made on both the self-supporting pellets and thin-film electrolytes coated onto a NiO–YSZ anode support. For the pellets, MELox 8Y showed the highest densification at lower sintering temperatures with 93% and 96% of the theoretical density at 1250 and 1300 °C, respectively. Although YSZ-HT showed a higher sintering rate than TZ-8Y, a sintering temperature of 1350 °C was required for both the powders to reach 95% of the theoretical density. For the thin-film electrolytes, on the other hand, YSZ-HT showed the highest sintering rate with a dense microstructure at a co-sintering temperature of 1250 °C. Our results indicate that besides the average particle size, other factors such as particle size distribution and post-processing play a significant role in determining the sintering rate and densification behavior of the YSZ powders. Additionally, a close match in the sintering shrinkage of the electrolyte and anode support is important for facilitating the densification of the thin-film electrolytes.

Highlights

Solid oxide fuel cells (SOFCs) are regarded as attractive power generation devices for various applications because of their high efficiency, low emissions, and flexible operation on hydrogen and hydrocarbon fuels [1,2,3]
The densification behavior of three different kinds of commercial 8 mol% Yttria-stabilized zirconia (YSZ) electrolyte powders was investigated by forming them into disc-shaped pellets as well as thin-film layers on top of the NiO–YSZ anode supports
For the densification of the self-supporting pellets, MELox 8Y exhibited the highest densification at lower sintering temperatures

Summary

Introduction

Solid oxide fuel cells (SOFCs) are regarded as attractive power generation devices for various applications because of their high efficiency, low emissions, and flexible operation on hydrogen and hydrocarbon fuels [1,2,3]. Most of the sintering studies reported in the literature for SOFC electrolytes were conducted in self-supporting electrolyte pellets These studies may not represent the densification behavior of the state-ofthe-art thin-film electrolytes because additional factors such as green density of the electrolyte coating and sintering properties of the support layer play an important role [31,32,33,34,35]. For this reason, we compared the densification of the YSZ powders in both the pellets and thin films coated onto an anode support

Experimental

Results and discussion

Conclusions