Nanoarchitectonics of Mg-doped Nd2NiO4 cathode for enhanced electrochemical performance and thermal behavior

Solid oxide fuel cells have received attention from researchers all over the world as a new energy source for the future. Various types of cathode materials for solid oxide cells have been developed to improve the cell’s performance. Novel cathode material Nd_2 − xMg_xNiO₄ (x = 0-0.025, NMNO), which with A₂BO₄ type R-P structure (a perovskite-like structure) was prepared by solution combustion method. The phase structure, microstructure, electrical performance, chemical stability, and thermal expansion compatibility with Gd_0.2Ce_0.8O_1.9 (GDC) electrolyte were studied. X-ray diffraction (XRD) analysis proved that the Nd_2 − xMg_xNiO₄ powders with R-P structure could be formed after calcined at 1150℃. Scanning electron microscopy (SEM) results showed that the NMNO powders had fine particulate microstructure composed of agglomerated nanoparticles with evenly distributed inter-particle pores. The conductivity of the cathode was measured by DC four-terminal method and the electrochemical performance was determined using electrochemical impedance spectroscopy (EIS). Results showed that doping with appropriate Mg²⁺ content could effectively increase the conductivity as well as improved the electrochemical performance of the Nd_2 − xMg_xNiO₄ cathode. A maximum conductivity of 122.62 S cm^− 1 could be found in the x = 0.015 sample at 450℃, and the polarization impedance of the symmetric cell with Nd_1.985Mg_0.015NiO₄ cathode at 800℃ in the air was measured to be 0.11Ω cm². The superior performance indicates that the Nd_2 − xMg_xNiO₄ is a promising cathode material for intermediate-temperature solid oxide fuel cells.

Graphical Abstract