Cobalt-free LaNi0.4Zn0.1Fe0.5O3-Q as a cathode for solid oxide fuel cells using proton-conducting electrolyte

A Zn-doping strategy is employed to tailor the LaNi0.5Fe0.5O3-delta material to improve its performance for proton-conducting solid oxide fuel cells (H-SOFCs). Zn can partially replace Ni in the LaNi0.5Fe0.5O3-delta lattice to form LaNi0.4Zn0.1Fe0.5O3-delta material. In contrast, ZnO secondary phase can be detected if attempts are made to partially replace Fe with Zn, and the nominal composition LaNi0.5Fe0.4Zn0.1O3-delta cannot be obtained. First-principles calculations indicate that the Zn-doping method lowers the formation energy of oxygen vacancy and decreases the hydration energy, benefiting its application as the cathode for H-SOFCs. As a result, the H-SOFC with the LaNi0.4Zn0.1Fe0.5O3-delta cathode generates a peak power density of 1226 mW cm(-2) at 700 degrees C. In contrast, the peak power density for the cell using the Zn free LaNi0.5Fe0.5O3-delta cathode only reaches 722 mW cm(-2) at the same testing temperature. The polarization resistance of the cell with the LaNi0.4Zn0.1Fe0.5O3-delta cathode is reduced to 0.043 Omega cm(2) at 700 degrees C, which is one of the smallest reported for H-SOFCs using cobalt-free cathodes. The high fuel cell performance coupled with the low polarization resistance for the Zn-modified LaNi0.5Fe0.5O3-delta suggests that the Zn-doping strategy would be an interesting way to promote the performance of the cobalt-free LaNi0.5Fe0.5O3-delta material for H-SOFCs. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.