固体氧化物燃料电池Sr系钙钛矿电极B位元素成分优化规律

采用第一性原理, 对元素周期表中3~6周期52种元素作为固体氧化物燃料电池(SOFC) Sr为A位系列钙钛矿结构电极材料B位替换元素的相关结构相的结合能进行了系统计算, 据此分析了各元素对生成立方相和六方相结构稳定性影响的趋势。通过对相关体系的成分比例进行推算, 讨论了这些实验体系在稳定性趋势图中的分布规律, 进一步对上述体系的实验数据进行分析, 得到了以Mo-Fe-Co连线为中心的成分优化区域。根据相关氧离子扩散模型的计算, 结果显示该区域形成的原因与氧空位形成能、迁移能以及禁带宽度均较为适中有关。以上理论结合实验的研究为电极材料的成分优化提供了理论指导。

Optimal Principle on Composition of B Site Elements in Perovskite Electrodes with Sr at A Site for Solid Oxide Fuel Cell

Based on ab inito method, the binding energies of SrBO₃ perovskite type electrode materials in solid oxide fuel cell in which B site chosen from 3^rd to 6^th periods elements were calculated. Effect of elements used in B site on the formation of cubic or hexagonal crystal structure was discussed. Structure stability diagram that contained three phases (unstable, cubic stable and hexagonal stable phases) was achieved. The distribution rule of composition points in this diagram was confirmed by inducing radius and valence data of cations at B site as validation data. Besides, there being plenty of experimental materials data in literature was introduced to this structure stability diagram, according to their compositions and lever rule. Distribution area of the obtained data was analysed and the results locate quite concentrated, indicating that the optimized area is centered by along the Mo-Fe-Co line. Within this area, our calculations find that formation energy and migration energy of oxygen vacancy as well as the band gap of the materials are suitable to be used as electrode materials in solid oxide fuel cell. The optimization area in SrBO₃ structure stability diagram can provide meaningful guidance for material selection.