Investigation of layered Ni0.8Co0.15Al0.05LiO2 in electrode for low-temperature solid oxide fuel cells

A symmetrical cell composed of Ce_0.9Gd_0.1O_2?δ electrolyte is constructed with 0.5 mm thickness and Ni_0.8Co_0.15Al_0.05LiO₂ (NCAL)-foam Ni composite electrodes. Electrochemical performance of the cell and electrochemical impedance spectra (EIS) are measured using the three-electrode method. The maximum power densities of the cell are 93.6 and 159.7 mW cm^?2 at 500 and 550 °C, respectively. The polarization resistances of the cathode are 0.393 and 0.729 Ω cm^?2 at 550 and 500 °C, indicating that NCAL has good ORR activity. HT-XRD results for NCAL do not show phase transitions or any additional new phases at elevated temperatures, indicating that NCAL has a stable phase structure. The surface characteristics of the NCAL powders are studied by XPS and FTIR. The results reveal that Li₂CO₃ and the cation-disordered “NiO-like” phase are formed on the surface of the layered NCAL structure due to prolonged exposure to air and contain a large number of oxygen vacancies. The cation-disordered “NiO-like” phase and Li₂CO₃ composite in the melt and partial melt states in the high temperature region are considered to possess very high ionic conductivity and lower activation energy for oxygen reduction reactions.