Coarse-grained molecular dynamics modeling and parameter analysis for sintered interface structures in sandwiched tri-layers reversible solid oxide fuel cell

Abstract

Degradation issue in reversible solid oxide fuel cell is one of the major challenges to limit its durability and reliability in long-term operation. Mechanical faulty occurs often on the interface region between the electrode and electrolyte layers. In this work, a sandwiched tri-layers design with symmetric composite electrodes structure is developed and investigated in terms of sintered structures and parameters. A coarse-grained method integrating with core-shell model is applied to simulate the sintering process for the nanoparticles and dense layer structure. Evolution and stress distribution of the obtained microstructures are predicted for understanding the sintering mechanism. Effects of sintering temperature, nanoparticle size, oxygen vacancy and composition are also investigated, expecting to achieve improved thermomechanical compatibility and low stress. It is revealed that surface diffusion is a major contribution on the neck formation, and a high stress is located on the interface region between the nanoparticles and dense layer. The sintered structure is controlled by the particle stress below 1473 K, while by both stress and diffusion above 1473 K. Low stress and high electrochemical performance can be achieved when the oxygen vacancy ranges in 1.65%–5.45%, or the mass fraction of yittria stabilized zirconia ranges in 50%–80% in the composite nanoparticles.