Performance and Stability of Nickelates Based Oxygen Electrodes for Solid Oxide Cells

This work is focused on the development of alternative oxygen electrode materials for Solid Oxide Fuel Cells (SOFCs) and Solid Oxide Electrolysis Cells (SOECs). Rare earth nickelates with general formula Ln2NiO4+δ (Ln = La, Pr or Nd) have shown good performance as oxygen electrodes with various electrolytes. In order to further enhance the physico-chemical properties, electrochemical performance of these nickelates as oxygen electrode, we have performed the substitution of nickel by other transition element such as cobalt. Two compositions of Ln2Ni1-xCoxO4+δ (Ln = La, Pr, Nd) and La1.5Pr0.5Ni1-xCoxO4+δ (x=0.1 and 0.2) were mainly considered and completely characterized using several techniques. The single cells were then prepared and electrochemically characterized using DC- and AC-techniques in the temperature range 700-900°C. The stability tests up to 250 h were also investigated at ±1 A.cm-2 current density at 800°C under both SOFC (with 100% H2) and SOEC conditions (with 50% H2 and 50% H2O feed gas mixture) indicating different degradation behavior.