An all-atom molecular dynamics-based method for evaluating particle-level stress and diffusion of sintering...

In this study, Von Mises stress at the electrode pore level and B-site atom/ion migration inside sintering particles are characterized and analyzed for La_0.9Sr_0.1Fe_0.9Co_0.1O_3-δ (LSFC)-Sm_0.2Ce_0.8O_1.9 (SDC) materials applied in reversible solid oxide fuel cells. An all-atom (AA) molecular dynamics (MD) approach is developed to predict diffusion and migration phenomena of ions in the LSFC-SDC electrodes, and further to evaluate the stress changes related to ion segregation. The effects on ion diffusion and stresses are also investigated in terms of sintering temperature, particle size, mass fraction and the number of A-site vacancies. It is found that the atom stress of sintered particles and ion migration are positively correlated; the diffusion coefficient of Fe and Co in sintered particles increases by 26% while their stress increases by 8%, when the sintering temperature is increased from 1073 to 1873 K. It is also found that smaller-sized particles may reduce the ion diffusion, while the lowest stress and ionic segregation are achieved when the optimized LSFC : SDC mass fraction ratio of 6 : 4 and an A-site deficiency of 3% (i.e., (La_0.9Sr_0.1)_0.97Fe_0.9Co_0.1O_3-δ) in LSFC are applied. This investigation and its findings provide a deeper understanding of the microscopical stress and diffusion within the sintered particles of LSFC-SDC electrodes.