La0.4Bi0.4Sr0.2FeO3-δ as Cobalt-free Cathode for Intermediate-Temperature Solid Oxide Fuel Cell

Abstract

La0.4Bi0.4Sr0.2FeO3-δ (LBSF) has previously been demonstrated to show the highest electrochemical performance in a series of bismuth doped lanthanum strontium ferrite La0.8-xBixSr0.2FeO3-δ where 0  x  0.8 as the cathode for intermediate-temperature solid oxide fuel cells. The cobalt-free electrocatalyst LBSF is further investigated in the present study using thermogravimetric analysis, oxygen temperature-programmed desorption method, iodometric titration and high-temperature X-ray diffraction refinement methods to reveal its structural properties including oxygen non-stoichiometry coefficient (δ), valence state of Fe, and lattice parameters at the different temperatures. In addition, the oxygen reduction process on the single phase LBSF is explored using the distribution of relaxation time method based on the electrochemical impedance spectroscopy measurements conducted in oxygen partial pressure from 0.01 to 1.0 atm. The LBSF cathode electrochemical performance is effectively improved by cooperating Sm0.2Ce0.8O1.9 (SDC), an oxygen ion conductor, resulting in interfacial polarization resistance less than 0.1 Ω cm 2 at 700 °C when SDC is used as the electrolyte.

A Highly Efficient Multi-phase Catalyst Dramatically Enhances the Rate of Oxygen Reduction

“…n of 1.16 for LF indicated that P1 (LF) corresponds to mass transport; while n = 0.516 for IF indicated that P2 (IF) is likely associated with the dissociation of O 2 into 2O ads . [34][35][36] The insensitivity of P3 (HF) to p O2 (n = 0.023) suggests that the HF process is likely associated with O 2À transfer across the electrode/electrolyte interface, which is a p O2 -independent process. 37 Shown in Figure 3D is the comparison of DRT plots for cells with a bare LSCF and an MP-LSCF electrode, as a function of testing time.…”

Promotion on electrochemical performance of Ba‐deficient Ba1 − xBi0.05Co0.8Nb0.15O3 − δcathode for intermediate temperature solid oxide fuel cells

“…In the refinement, the +5 valence state of Bi doped in the B‐site was confirmed. Bi may occupy in the A site and B site. For the B‐site in the perovskite phase of ABO 3 , it has medium ion radius (0.62–1.00 Å).…”

“…Bi may occupy in the A site and B site 50,51 . For the B-site in the perovskite phase of ABO 3 , 52 it has medium ion radius (0.62-1.00 Å).…”

Effects of sintering temperature on the structural and electrochemical properties of SrFe0.5Ti0.5O3‐δ perovskite cathode

“…The equivalent circuit (Figure ) was generated after fitting the EIS spectra. The R 1 in this result represented the ohmic, electrolyte, and wire resistances and was not considered for the cathode ASR . At the medium‐ and low‐frequency regions, R 2 and R 3 were measured, respectively.…”