Co-electrolysis of steam and carbon dioxide in large area solid oxide cells based on infiltrated mesoporous oxygen electrodes

Abstract

Infiltration of nano-catalysts in ionic-conductive backbones is receiving increasing attention to fabricate highly performing electrodes for Solid Oxide Cells application. In particular, nanostructured, high surface area scaffolds based on ceria and infiltrated with functional perovskites have already proved their excellent catalytic activity as oxygen electrodes. A major challenge for this type of nanocomposites is keeping the enhanced performance when up-scaling to large area cells and during long term operation. In this work, Ce0.8Gd0.2O1.9-La0.6Sr0.4Co0.2Fe0.8O3-δ infiltrated mesoporous oxygen electrodes were fabricated and tested in state-of-the-art 25 cm2 area fuel electrode supported solid oxide electrolysis cells. Injected currents as high as 11.2 A (0.7 A cm−2) at 1.3 V were measured in co-electrolysis mode at 750 °C showing improved performances with respect to button cell counterparts. Stability tests at injected currents of 8 A (0.5 A cm−2) for more than 600 h yielded a degradation rate of 126 mV kh−1 mainly related to the metallic nickel depletion approaching the fuel electrode-electrolyte interface, proving the stability of the oxygen electrode under highly demanding operating conditions. The excellent results presented here anticipate the relevance of nanostructured infiltrated electrodes for the next generation of enhanced Solid Oxide Cells.