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

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 selfsupporting 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 ℃, respectively. Although YSZ-HT showed a higher sintering rate than TZ-8Y, a sintering temperature of 1350 ℃ 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 ℃. 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.

A review on recent status and challenges of yttria stabilized zirconia modification to lowering the temperature of solid oxide fuel cells operation

“…Xiao et al 119 combined the YSZ powder with alumina to fabricate the electrolyte component in order to increase the conductivity properties through the co-precipitation method. Panthi et al 121 focused on the densification behavior of YSZ electrolyte. Yeh et al 120 manipulated the plasma emission monitoring method to synthesize the thin film of YSZ electrolyte.…”

“…74,121 The targeted conductivity of modification of YSZ electrolyte must be exceeded >0.1 S cm -1 to enable high performance of SOFCs power generation systems to be realized for transportation and portable applications. 74,121 The targeted conductivity of modification of YSZ electrolyte must be exceeded >0.1 S cm -1 to enable high performance of SOFCs power generation systems to be realized for transportation and portable applications.…”

“…121 Da Silva et al 72 revealed the best result to produce homogenous, straight structure, clear and clean, uniform, and high densification of YSZ electrolyte with used glycine route as fuel in combustion method. Thus, the synthesis method is important to influence the phase purity and homogeneity of YSZ electrolyte.…”

“…104,121 Frison et al 83 fabricated the biphasic amorphous crystalline thin film of YSZ microstructure~200 nm thick with homogenous and dense structure via RF-sputtering method to maintain the mechanical properties in thick size. To get higher ionic conductivity, one solution is to provide thick electrolyte to reduce the ohmic resistance effect.…”

Tubular solid oxide fuel cells fabricated by a novel freeze casting method

“…Thin functional layers were applied onto the pre-sintered anode tubes by dip coating as described elsewhere. 12,37 To achieve the desired thicknesses, dip coating was conducted two times for the electrolyte layer and three times for the anode functional, cathode functional, and cathode current collector layers. Each dip coating was followed by drying in air for 5-10 minutes.…”