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 more effective 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. Aluminum titanate was introduced into the porous YSZ anode scaffold to facilitate a step-wise chemical reaction to anchor the nickel metal catalyst as determined by XRD. SEM observation of thermally treated nickel infiltrated scaffolds indicates excellent preservation of the nickel network at 800 C for 72 hrs. Electrochemical tests show not only decreased degradation rates, but also increased initial performance levels due to the additive.

Ni migration in solid oxide cell electrodes: Review and revised hypothesis

“…Addition of a Ni-YSZ wetting agent that makes the interface free energy more negative is also a possibility. This is probably what happens by addition of Al and Ti in the form of Al 2 TiO 5 , which Law and Sofie [53] and Driscoll et al [54] used to "anchor" Ni-particles to the YSZ to prevent coarsening and migration of Ni particles. Infiltration with aluminum titanate increased Ni catalyst stability in Ni-YSZ electrode such that "the time required for degradation to 90% of initial current output was increased by a factor of 115" [54].…”