Performance optimization of LSCF/Gd:CeO$_2$ composite cathodes via single-step inkjet printing infltration

Abstract

The effect of solid oxide fuel cell cathode microstructure modification on its electrochemical activity is investigated. Inkjet printing infiltration was used to develop a nano-decoration pattern on the composite cathode scaffolds. Two types of composite La$_{0.6}$Sr$_{0.4}$Co$_{0.2}$Fe$_{0.8}$O$_{3−δ}$:Ce$_{0.9}$Gd$_{0.1}$O$_{1.9}$ cathodes with different volume ratios (60:40 and 40:60 vol%) were fabricated using inkjet printing of suspension inks. The electrodes were altered by single-step inkjet printing infiltration of ethanol-based Ce$_{0.9}$Gd$_{0.1}$O$_{1.9}$ ink. After heat treatments in air at 550 °C the cathodes’ surfaces were shown to be nano-decorated with Ce$_{0.9}$Gd$_{0.1}$O$_{1.9}$ particles (~20–120 nm in size) dispersed uniformly onto the electrode scaffold. The nano-engineered microstructure enhanced the active triple phase boundary of the electrode and promoted the surface exchange reaction of oxygen. Electrochemical impedance tests conducted on symmetrical cells showed a reduction in the polarization resistance of between 1.3 and 2.9 times. The effect was found to be more pronounced in the 60:40 vol% composite cathodes. Ageing of infiltrated electrodes up to 60 h in air revealed enhanced stability of gadolinium doped ceria nanoparticles decorated electrodes ascribed to the suppression of SrO surface segregation. This work demonstrated that single-step inkjet printing infiltration can produce reproducible performance enhancements and thus offers a cost-effective route for commercial solid oxide fuel cell infiltration processing.