Exploring mixed proton/electron conducting air electrode materials in protonic electrolysis cell

In this work, we investigate and compare the performance and cell polarization resistance of Ba_0.5La_0.5CoO_3−δ (BLC) and double perovskite oxide BaGd_0.8La_0.2Co₂O_6−δ (BGLC) anode on cathode supported protonic steam electrolysis cells using a 20 μm SrZr_0.5Ce_0.4Y_0.1O_3−δ electrolyte with Ni-SZCY541 composite as the cathode. The kinetics of protons through the bulk and across the gas electrolyte interfaces of both anode materials were also studied by direct measurement of their tracer diffusions using time-of-flight secondary ion mass spectrometry depth profiling (TOF-SIMS). Cell terminal voltages of 1.74 and 1.93 V, were observed at a current density of 0.5 A cm⁻² for both BLC and BGLC whereas a hydrogen evolution rate of 121.85 and 111.15 μmol cm⁻² every minute was also obtained at the same current density, translating to a current efficiency of 78 and 72% respectively. Hydrogen tracer diffusion studies confirm BGLC can incorporate protons into the bulk relative to BLC even though the present steam electrolysis results show a better performance for BLC at 600 °C.