Modeling Analysis of Bi-Layer Ni-(ZrO2)x(Y2O3)1−x Anodes for Anode-Supported Intermediate Temperature-Solid Oxide Fuel Cells

Abstract

Intermediate temperature-solid oxide fuel cell (IT-SOFC) Ni-(ZrO2)x(Y2O3)1−x (Ni-YSZ) anodes formed by two layers, with different thicknesses and morphologies, offer the possibility of obtaining adequate electrochemical performance coupled to satisfactory mechanical properties. We investigate bi-layered Ni-YSZ anodes from a modeling point of view. The model includes reaction kinetics (Butler-Volmer equation), mass transport (Dusty-Gas model), and charge transport (Ohm’s law), and allows to gain an insight into the distribution of the electrochemical reaction within the electrode. Additionally, the model allows to evaluate a reciprocal overall electrode resistance 1/Rp ≈ 6 S·cm−2 for a bi-layer electrode formed by a 10 µm thick active layer (AL) composed of 0.25 µm radius Ni and YSZ particles (34% vol. Ni), coupled to a 700 µm thick support layer (SL) formed by 0.5 µm radius Ni and YSZ particles (50% vol. Ni), and operated at a temperature of 1023 K. Simulation results compare satisfactorily to literature experimental data. The model allows to investigate, in detail, the effect of morphological and geometric parameters on the various sources of losses, which is the first step for an optimized electrode design.

Keywords

• intermediate temperature-solid oxide fuel cell (IT-SOFC)
• Ni-(ZrO2)x(Y2O3)1−x (Ni-YSZ) composite
• anode
• anode-supported cell
• bi-layer electrode
• modeling