The Influence of Grain Size on La0.6Sr0.4Co0.2Fe0.8O3-δ Thin Film Electrode Impedance

Abstract

Dense thin-film La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3- (LSCF6428) electrodes of thickness 450 nm were symmetrically deposited onto either side of gadolinium doped ceria (CGO) electrolyte pellets by spray pyrolysis. Three film electrodes were fabricated with three different average grain sizes; 285, 370 and 535 nm. The grain size was controlled by changing the electrode sintering duration from 2 to 12 h and 36 h at 1373 K. The polarization resistance (R p ) of the electrode was observed to decrease with decreasing grain size in both fuel cell and electrolysis cell modes. The impedance curves of the electrodes were dominated by a large low frequency arc, attributed to a surface electrocatalytic process. The electrode performance was enhanced initially on the application of 0.25 and 0.5 V potential bias for 5 min. © 2011 The Electrochemical Society.