Rational modification of traditional La0.5Sr0.5(Fe/Mn)O3 cathodes for proton-conducting solid oxide fuel cells: Inspiration from nature

By screening a series of La0.5Sr0.5MnO3-δ (LSM)-La0.5Sr0.5FeO3-δ (LSF) solid solutions using first-principles calculations, an optimal solid solution of LSM and LSF was chosen as the cathode for proton-conducting solid oxide fuel cells (H–SOFCs). In terms of oxygen vacancy formation energy, O2 adsorption energy, bond length of adsorbed O2, and O p-band center, La0.5Sr0.5Mn0.875Fe0.125O3 (LSMF125) and La0.5Sr0.5Mn25Fe0.75O3 (LSMF75) exhibited superior properties. Subsequent experimental investigations revealed that the H–SOFC with the LSMF75 cathode performed better than the cell with the LSMF125 cathode. The structure analysis revealed that LSMF75 has both Mn and Fe cations on its surface, similar to the designs of several naturally occurring enzymes, hence the increased cathode activity. By improving the LSMF75 cathode further, the cell utilizing the LSMF75 cathode attained a peak power density of 1238 mW cm-2 at 700 °C, which was much greater than that of the cells using the LSM or LSF cathodes, illustrating the benefits of using the LSM-LSF solid solution. Additionally, the good chemical stability of the LSMF75 cathode was maintained, allowing for 150 h of stable operation under operational conditions.