A multiscale framework to predict electrochemical characteristics of yttrium doped Barium Zirconate based solid oxide cells

A multiscale model is developed combining physics at atomistic, meso and continuum scales to predict the electrochemical characteristics of Current-Voltage curves in Yttrium doped Barium Zirconate based solid oxide cells. The most probable reaction pathway involving proton transfer from the surface of electrodes to the electrode/air/electrolyte Triple Phase Boundary from where it moves to the electrolyte is proposed, and their reaction barriers have been predicted from Density Functional Theory calculations. The model is validated against experimental observations. The environment, such as the amount of H₂ (reducing) and O₂ (oxidizing) gases the electrolyte is equilibrated in, affects the type of charge carriers while the temperature affects their rate of transport. Both these factors affect the rate of reactions in the proposed pathway. These effects are well manifested in the predicted electrochemical characteristics. The reducing environments are suitable for fuel cell mode operation and, the oxidizing environments are suitable for electrolyzer cell mode operations. The activation energy for conductivity in oxidizing environments is higher making it less amenable for low-temperature operation than in reducing environments. A data-driven sensitivity analysis is performed from which a non-intuitive parameter, permittivity of the electrolyte, is predicted to be important for Solid Oxide Cell performance.