Chemical compatibility of solid oxide fuel cell air electrode Pr4Ni3O10±δ with commercial electrolytes

Abstract

The chemical reactivity between Pr4Ni3O10±δ (3-PNO) electrodes andY0.08Zr0.92O1.96 (YSZ), Ce0.9Gd0.1O1.95 (GDC), and La0.9Sr0.1Ga0.8Mg0.2O2.85(LSGM) electrolytes was analyzed by electrochemical impedance spectroscopyand X-ray diffraction. 3-PNO powders were synthesized by two different chemicalroutes, one of them uses hexamethylenetetramine (HMTA) as a complexingagent (route A) while the other citrates (route B). The samples observed by scanningelectron microscopy presented different microstructures; route A powderspresent small submicronic grains with an open microstructure while route Bpowders are formed by larger well-connected grains. The polarization resistance(RP) values for 3-PNO/YSZ cells are one order of magnitude higher than thoseof 3-PNO/GDC and 3-PNO/LSGM cells. The RP for both cells 3-PNO/GDCand 3-PNO/LSGM and its evolution in time suggest that chemical reactivitytakes place during the adhesion treatment and electrochemical measurements.The microstructure plays a crucial role in RP and the degradation rate; 3-PNOobtained by route A (3-PNO-HMTA) exhibits the best electrochemical performancesince these powders present a well-loosemorphology and a large exposedarea. However, this fact makes them active chemically, so the increase of RPwith time is slower for 3-PNO electrodes prepared by route B (3-PNO-Cit), sincethe rate of chemical reactivity with the electrolyte is slower.