Enhanced electrochemical performance of co-synthesized La₂NiO_4+δ-Ce_0.55La_0.45O_2-δcomposite cathode for IT-SOFCs

In this paper, a composite cathode material consisted of 70 wt % La₂NiO_4+δand 30 wt % Ce_0.55La_0.45O_2-δ(LNO-LDC) was synthesized by co-synthesized method. The LNO-LDC composite cathode was coated on Sm_0.2Ce_0.8O_1.9electrolyte and its electrochemical performance was evaluated. The co-synthesized LNO-LDC cathode showed excellent electrochemical performance, demonstrating a polarization resistance of 0.06 Ω cm²at 800 °C, which is significantly lower than that of physically mixed LNO-LDC composite cathode under the same operating condition. The enhanced electrochemical performance was mainly due to the reduced particle size and improved dispersion uniformity of the two phases, leading to increase of the two phase boundary (2 PB) and triple-phase boundary (3 PB). Furthermore, impedance spectra under various oxygen partial pressure determined that the rate-determining step of the co-synthesized LNO-LDC cathode is the charge transfer process. The obtained results indicated that co-synthesized method is a simple and effective method to fabricate high-performance LNO-LDC composite for intermediate temperature solid oxide fuel cells (IT-SOFCs).