Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H2 production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV) in a one-atmosphere set-up. For the oxygen electrode, nano-structured La0.75Sr0.25MnO3 (LSM25) is impregnated into a LSM25/yttria stabilised zirconia (YSZ) composite, whereas for the steam electrode, nano-structured Ni and Ce0.8Gd0.2O2−δ (CGO) is impregnated into a Sr0.94Ti0.9Nb0.10O3−δ (STN) backbone. In the present study, the best performing oxygen electrode is a LSM25-YSZ composite with 20% porosity and impregnated with a LSM25 solution measuring a polarisation resistance (Rp) of 0.12 Ω cm2 at 850 °C in oxygen. For the steam electrode, the best performance is obtained for a STN backbone, sintered at 1200 °C and impregnated with CGO/Ni, with an Rp of 0.08 Ω cm2 at 850 °C in 3% H2O/H2.