Electrochemical Performance and Microstructure of The LNF-SDC Composite Cathode for SOFC

Abstract

Symmetric cells consisting of the LaNi 0.6 Fe 0.4 O 3 (LNF)-Sm 0.2 Ce 0.8 O 1.9 (SDC) composite cathodes and 8 mol%Y 2 O 3 -stabilized ZrO 2 (YSZ) electrolyte have been investigated in order to evaluate the oxygen reduction performance of the composite cathode by AC impedance analysis. Cell performance and cathodic overvoltage were examined for cells consisting of the Ni-YSZ cermet anode, YSZ electrolyte, and composite cathode. The addition of 50 wt% SDC to LNF resulted in the lowest polarization resistance. A cell using the 50 wt% LNF + 50 wt% SDC composite cathode showed the maximum power density and the cathodic overvoltage for this cell showed as half as lower than that for a cell using the LNF cathode under the same condition. Enhancement of the electrochemical performance in the LNF-SDC composite cathode is most likely to be caused by the SDC particles connecting LNF particles with the electrolyte surface.

Determination of Kinetic Parameters and Identification of the Rate-Determining Steps in the Oxygen Exchange Process for LaNi0.6Fe0.4O3−δ

“…Positive features of the LaNi 0.6 Fe 0.4 O 3− δ material are the absence of cobalt and strontium in the composition, which inhibit degradation processes [ 18 , 19 ]; a satisfactory coefficient of thermal expansion ((11.4–13) × 10 −6 K −1 [ 15 , 20 , 21 ]) close to electrolytes Ce 0.9 Gd 0.1 O 2– δ (12.5 × 10 −6 K −1 [ 22 ]), BaCe 0.8 Y 0.2 O 3− δ (11.6 × 10 −6 K −1 [ 23 ]), and La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3− δ (11.4 × 10 −6 K −1 [ 24 ]); and the absence of chemical interaction with chromium-containing steels [ 25 ]. The electron conductor LaNi 0.6 Fe 0.4 O 3− δ can effectively function as a current collector for bilayer electrodes containing functional layers composed of layered nickelate [ 26 , 27 , 28 , 29 ] or composite electrodes [ 30 , 31 , 32 ]. The method of synthesis greatly affects the dispersibility, morphology, particle size, and sinterability of the material.…”