Anchoring of Infiltrated Nickel Electro-Catalyst by Addition of Aluminum Titanate

Abstract

Solid oxide fuel cell electrodes based on catalyst coatings offer substantial potential for creating improved anode and cathode structures. Infiltrated anodes based on nickel metal can yield finer catalyst phase distribution at volumetric concentrations well below percolation for traditional cermets. The coarsening of nickel after high temperature thermal treatment poses substantial degradation to the deposited structure, therefore, methods of anchoring the nickel metal to the yttria-stabilized zirconia (YSZ) scaffold have been evaluated to stabilize fine scale electro-catalyst particles. Metastable aluminum titanate was introduced into the porous YSZ anode scaffold to facilitate a step-wise chemical reaction in the formation of nickel aluminate followed by zirconium titanate to anchor the nickel metal catalyst. SEM observation of thermally treated nickel infiltrated scaffolds indicates excellent preservation of the nickel network at 800 C for 72 h. Electrochemical tests show not only decreased degradation rates, but also increased initial performance levels due to the additive.

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

“…In the presented manufacturing conditions, ALT spontaneously decomposes to Al 2 O 3 and TiO 2 , , . Part of the Al 2 O 3 initially reacts with NiO to form NiAl 2 O 4 , , , , proportionally to the amount of Al 2 O 3 made available through ALT doping. For the oxidized samples, an enhancement of the scaled characteristic strength was observed for all of the ALT doping amounts.…”

“…TiO 2 addition was found to have a similar effect , . Previous research has observed that the addition of aluminum titanate Al 2 TiO 5 , (ALT) to the Ni/YSZ system stabilizes SOFC performance in terms of slow degradation rates and high power output. Since there is little fundamental data on the mechanical strength and fracture mechanism of ALT doped systems, this study aims to complement the electrochemical benefits offered by Al 2 TiO 5 doping investigating its effect on the mechanical performance of NiO/YSZ and Ni/YSZ anodes.…”

La, Y and Nb Doped SrTiO3 Anodes for Electrolyte Supported SOFC

“…To prevent coarsening of Ni-YSZ anode, various alternative methods have been researched such as strong metal support interaction (2) between Ni and other transition metal oxides (TMO) e.g., TiO 2 , CeO 2 , Nb 2 O 5 . Some researchers (3)(4)(5) have observed that TMO-Ni-YSZ anode made from solid-state route (~1450°C) forms solid solution (zirconium titanates, cerium zirconates), which acts as chemical anchor and helps in diminishing the effect of nickel sintering at the operating temperature of SOFC. Strontium titanate (SrTiO 3 ) is a good alternate to Ni based anode as it possesses desirable thermal, chemical stability and show mixed ionic and electronic conducting behavior at low oxygen partial pressure (6)(7)(8).…”

“…Electrolyte supported SOFC uses the dense electrolyte as structural support to thin electrodes, which are deposited on both side of it after sintering of electrolyte (3). As electrolyte is the structural component of the cell, gas transport in the cathode is not a serious concern and crack formation in the anode by re-oxidation does not destroy the cell structure (3,(19)(20) and thinner anode support helps in easy hydrogen diffusion to the reaction site (triple phase boundary). Small amount of Ni is added to single and bi-doped SrTiO 3 anodes for sufficient electronic conductivity and catalytic activity towards H 2 oxidation.…”

Thermally Stabilized Nickel Electro-Catalyst Introduced by Infiltration for High Temperature Electrochemical Energy Conversion

“…One previously reported means of inhibiting nickel coarsening is through the use of aluminum titanate (Al 2 TiO 5 ) as an in-situ chemically formed anchor (10). The concept of this approach is to place aluminum titanate (ALT) at a nickel/YSZ interface where it can decompose into alumina and titania constituents.…”