Planar copper containing anode-supported solid oxide fuel cells

Abstract

Planar copper-containing anode supported Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs) were produced by single step cosintering. The anode and the electrolyte were realized through water-based tape casting, the cathode being added by screen printing. A 5 mol% of Lithium oxide addition allowed reducing the Gadolinia-Doped Ceria (GDC)-based electrolyte sintering temperature below the copper oxide melting point. IT-SOFCs sintered at 950°C revealed a power density peak of 26 mW cm-2 at 650°C in H2, the maximum CuO amount within the anodic cermet being limited at 35 vol%. To improve the cell performance, the anode electrolyte thickness ratio was increased, in order to take advantage by the compressive tensile state induced by the supporting to the thinner layer, this leading to a further sintering temperature reduction and to avoid cracks due to the thermal expansion coefficient (TEC) mismatch existing between anode and electrolyte. IT-SOFCs at 900°C showed a power density peak of 200 mW cm-2 at 700°C in H2. Electronic impedance spectroscopy pointed out anode performances comparable with those obtained by using conventional Ni-based cermet electrodes. In biogas, 45 vol% CuO containing SOFC achieved a power density peak of 38 mW cm-2 at 700°C.