Preparation and testing of metal/Ce0.80Gd0.20O1.90 (metal: Ni, Pd, Pt, Rh, Ru) co-impregnated La0.20Sr0.25Ca0.45TiO3 anode microstructures for solid oxide fuel cells

Abstract

La0.20Sr0.25Ca0.45TiO3 (LSCTA-) is a novel mixed ionic and electronic conductor (MIEC) material which can act as a potential replacement Solid Oxide Fuel Cell (SOFC) anode ‘backbone’ microstructure, for the current state-of-the-art Ni-based cermet. By impregnating this ‘backbone’ with electrocatalytically active coatings of metal oxides and metallic particles, it is possible to create high performance SOFC anodes which offer improved redox stability and tolerance to non-optimal fuel gases. Here, we present short-term test data for SOFC containing LSCTA- anode ‘backbones’ impregnated with a variety of catalyst systems including: Ni/CGO, Pd/CGO, Pt/CGO, Rh/CGO and Ru/CGO. Electrolyte-supported SOFC containing Ni/CGO impregnated anodes showed large reductions in Area Specific Resistance (ASR), in comparison to previous generation research (0.55 Ω cm2 versus 1.2 Ω cm2, respectively). Exchange of the Ni component, for Pd and Rh, led to much lower ASR of 0.39 Ω cm2 and 0.41 Ω cm2 (in 97% H2:3% H2O, at 900°C and 0.8 V), respectively. Equivalent circuit fitting of AC impedance spectra revealed the absence of an anode charge transfer process for the Rh/CGO catalyst system above 875°C, in comparison to all other systems, identifying this system as a potential replacement for the Ni-based cermet.