Recent progress on multi-scale calculation of perovskite-based proton-conducting electrolytes for proton ceramic fuel cells

Proton ceramic fuel cells have received much attention as efficient energy conversion technologies due to their relatively mild operating temperature, low cost and excellent performance. Perovskite-type oxides are the core electrolyte materials that affect the efficiency of proton ceramic fuel cells due to the inherent property of allowing proton traversal. In this paper, we provide a systematic review of multi-scale simulations, which can reveal proton absorption and conduction mechanisms from the atomic scale to the macroscopic scale to screen novel electrolyte materials and reveal their constitutive relationships. To accelerate proton conduction, atomic-scale simulations based on first-principles calculations of density-functional theory have provided an important theoretical tool for revealing the proton transport mechanism of perovskite-based proton conductors and optimizing the material design in recent years. The integration of density-functional theory with conventional experiments, molecular dynamics, and machine learning is emphasized, which will accelerate the development process of high-performance electrolytes for proton ceramic fuel cells. Firstly, a major overview of the application of first-principles and molecular dynamics calculations to the study of perovskite-based proton-conducting electrolytes is presented, including the electronic structure and its phase stability, thermodynamic and chemical properties, and the kinetic properties and mechanisms of proton absorption and conduction. The integrated pairing of multi-scale optimization of perovskite-based proton-conducting electrolytes and the use of machine learning and high-throughput screening to optimize the important decisions of candidate materials are also discussed. Some representative examples are given in turn. In particular, the focus is summarized on defect regulation mechanisms, proton migration path resolution, the process of protons crossing grain boundaries, and the prediction of novel materials. The auxiliary relationship between theoretical calculations and experimental characterization is also explored. Finally, from a personal perspective, the current challenges and future directions of computationally driven proton conductor electrolyte materials with multi-scale interconvergence are discussed.