Role of oxygen anion diffusion in improved electrochemical performance of layered perovskite LnBa1 − ySryCo2 − xFexO5 + δ (Ln = Pr, Nd, Gd) electrodes

• On Sr and Fe doping the diffusivity of PBCO was estimated to increase.
• Higher diffusivity in PBSCO and PBCFO can be correlated to the reduction in ASR.
• The diffusivity was estimated to be maximum in co-doped PBSCFO.
• High diffusivity in PBSCFO explains the measured high peak power density.
• The diffusivity follows the trend PBSCFO > NBSCFO > GBSCFO for co-doped structures.

Molecular dynamics simulations were utilized to calculate self-diffusion coefficients in double perovskite LnBa1 − ySryCo2 − xFexO5 + δ (Ln = Pr, Nd, Gd) electrodes. Anisotropic oxygen diffusion was observed in the a–b plane for all the studied structures. In order to assess the role of A-site and B-site dopants such as Sr and Fe, the diffusion coefficient of oxygen ion in PrBaCo2O5.5 was estimated and compared to PrBa0.5Sr0.5Co2O5.5 and PrBaCo1.5Fe0.5O5.5. On doping with 50% Sr at A′-site, a 2.77 fold increase in diffusivity value was predicted at 873 K as compared to the undoped structure. Similar levels of increase in diffusivity values were observed with 25% Fe doping relative to PrBaCo2O5.5. On co-doping Sr and Fe, oxygen diffusion coefficient was observed to be of the highest value (1.18 × 10− 7 cm2 s− 1) at 873 K for PrBa0.5Sr0.5Co1.5Fe0.5O5.5. Changing the A-site lanthanide cation from Pr to Gd and Nd, led to the reduction in diffusivity value in the order of Pr3 + > Nd3 + > Gd3 +. The calculated diffusivity was observed to be higher, wherever an improved electrochemical performance is reported, highlighting the important role of oxygen anion transport.