Effect of Aluminum Titanate (Al₂TiO₅) Doping on the Mechanical Performance of Solid Oxide Fuel Cell Ni‐YSZ Anode

Abstract

The mechanical behavior of un‐doped and 1–10 wt.% aluminum titanate doped NiO‐YSZ anodes was evaluated in the oxidized and reduced state of the material. Sample bars 25 × 5 × 2 mm were fabricated and tested in a three‐point bending apparatus and statistical analyzes of the collected data were performed. A remarkable enhancement of the flexural strength was found both for the reduced and oxidized state of the material when compared to the un‐doped samples. In both cases, the development of a secondary phase was observed proportional to the doping amount of aluminum titanate. Morphological analysis along with preliminary phase identification and suspected mechanisms for strength enhancement are presented and discussed.

Operando Studies of Redox Resilience in ALT Enhanced NiO-YSZ SOFC Anodes

“…24,[27][28][29][30][31][32] Specifically, aluminum titanium oxide (Al 2 TiO 5 or ALT) added to Ni-YSZ cermet electrodes has been shown to improve SOFC performance, longevity, and strength. [33][34][35] C) under reducing conditions. [33][34][35] Of the secondary phases that form, NiAl 2 O 4 is believed to suppress Ni coarsening, while the Zr 5 Ti 7 O 24 may have mixed ion electron conducting properties.…”

Mitigating Carbon Formation with Al2TiO5-Enhanced Solid Oxide Fuel Cell Anodes

“…Recent reports have shown that small addition (≤5% by mass) of aluminum titanate (Al 2 TiO 5 /ALT) to Ni–YSZ anodes in electrolyte-supported SOFCs improves the thermal expansion match between the Ni-based anodes and the YSZ electrolyte. ALT also appears to prevent the coarsening of Ni particles. − Additionally, ALT-doped anodes show a variety of other benefits including increased electrochemical performance in cells operating with H 2 , improved mechanical strength, and increased resilience to both electrochemical and environmental redox cycling. ,− During the processing of anodes, ALT reacts with NiO and YSZ to form nickel aluminate (NiAl 2 O 4 ) and zirconium titanate (Zr 5 Ti 7 O 24 ), respectively. Upon reduction, these materials separate, forming elemental Ni and oxides of aluminum and titanium.…”

Enhancing Ni-YSZ Anode Resilience to Environmental Redox Stress with Aluminum Titanate Secondary Phases

“…28−31 One successful example of this is infiltrating free-standing Ni-YSZ cermets with small amounts of oxide dopants. 32,33 Previous studies have shown that the addition of aluminum and titanium based oxides can improve the thermal expansion match between the Ni-based anodes and a YSZ electrolyte 34,35 as well as prevent Ni particle coarsening at high temperatures leading to enhanced SOFC strength 33,36 and improved performance and longevity. 32,37,38 An example of a promising aluminum and titanium based oxide is aluminum titanate (Al 2 TiO 5 or ALT).…”

“…When added to Ni-YSZ anodes, ALT reacts with NiO and YSZ during processing to form secondary phases that include a nickel aluminate spinel (NiAl 2 O 4 ) and a zirconium titanate (Zr 5 Ti 7 O 24 ). In addition to providing standard Ni-YSZ anodes with improved mechanical strength and electrochemical performance, 36,39 these secondary phases have also been shown to enhance anode resilience to repeated electrochemical redox cycling by a factor of 2 compared to conventional, undoped cermet anodes. 22 Experiments described below expand upon the previous findings by examining how ALT doping improves the anode resilience to environmental redox cycling from direct exposure to H 2 O and O 2 .…”

“…Strategies intended to improve SOFC tolerance to redox cycling have focused on strengthening anodes with secondary materials. − One successful example of this is infiltrating free-standing Ni-YSZ cermets with small amounts of oxide dopants. , Previous studies have shown that the addition of aluminum and titanium based oxides can improve the thermal expansion match between the Ni-based anodes and a YSZ electrolyte , as well as prevent Ni particle coarsening at high temperatures leading to enhanced SOFC strength , and improved performance and longevity. ,, An example of a promising aluminum and titanium based oxide is aluminum titanate (Al 2 TiO 5 or ALT). When added to Ni-YSZ anodes, ALT reacts with NiO and YSZ during processing to form secondary phases that include a nickel aluminate spinel (NiAl 2 O 4 ) and a zirconium titanate (Zr 5 Ti 7 O 24 ).…”