Optimisation of the Solid Oxide Fuel Cell (SOFC) cathode material Ca₃Co₄O_9-δ

This paper focuses on the electrochemical potentialities of the 2D misfit compound Ca3Co4O9-delta, so far mainly investigated for its thermoelectric properties. Its expansion coefficient (TEC = (9-10) x 10(-6)degrees C-1) and its chemical stability are compatible with standard CGO IT-electrolyte and the first optimisation steps of the deposited cathode have been performed with the aim to minimise the ASR and increase the cell durability. Particular attention has been paid on the effect of thickness and microstructure for pure and composite cathodes. The electrode reaction was performed on symmetrical cells. The preliminary results presented here show that the composite (70 wt.% Ca3Co4O9-delta-30 wt.% CGO) gives the lowest ASR values compare to single-phased electrodes. Strikingly, the ASR values increase for thinner deposited layers. The effect of various current collectors (gold grid vs. platinum paste) has been also checked. (C) 2011 Elsevier B.V. All rights reserved.