固体氧化物燃料电池电极微观结构内的多物理场耦合效应及多目标优化研究

The electrodes are the key components of the solid oxide fuel cells (SOFC). The performances of SOFC are highly dependent on the microstructure of the electrodes, which can be improved via the optimization on the microstructure pattern of electrodes. Currently, most of the microstructure designs for electrodes only consider the gas transport in the porous structure of electrodes while the performances of the electrical conductivity, thermal heat transfer and stress endurance are little addressed. This project will firstly develop a 3-dimensional reconstruction methodology for the geometric characterization of the electrode microstructure using the pore-solid fractal theory and random probability theory. A complete mathematic dusty-gas model (DGM) and the numerical method are developed for simulating the multicomponent gas diffusion in the porous of electrodes. The mechanisms for the gas diffusion with the multiple chemical reactions in the pore space of electrodes are illustrated by numerical simulations. The performances of thermal conductivity, electrical conductivity and stress endurance with electrodes are investigated by the Monte Carlo simulation and mesomechanics based finite element analysis. The interactions and effects between different fields for electrodes are examined. A multi-objective programming model with synthetically considering the performances of the mass and heat transfer, electrical conductivity, and stress endurance as well as the solving algorithm are developed for microstructure optimization of electrodes. The results provide theory guidance and technical support to achieve a high level microstructure design for electrodes of SOFC.

电极是组成固体氧化物燃料电池（SOFC）的关键部件之一，开展电极微观结构优化研究对于提高SOFC整体性能具有重要意义。目前电极微观结构设计多是仅考虑电极孔隙结构的气体传输性能，很少考虑到电极微观固体结构的导电、传热和抗应力等影响电池热稳定性方面的性能。鉴于此，本项目从构建基于孔隙-固体分形理论和随机概率理论的电极微观几何结构三维表征模型出发，建立电极微观孔隙结构多组分气体传输的完整DGM模型和数值模拟方法，研究阳极微观孔隙结构内存在多重化学反应的气体传质机理过程；采用蒙特卡罗和细观力学有限元分析方法研究电极微观固体结构的导热、非线性导电和抗应力性能，揭示电极微观结构在气体传输、导电、传热和应力等性能变化的多物理场耦合效应机理；建立综合考虑电极的导电、传热传质和抗应力性能的电极微观结构多目标优化理论、方法和实验验证。项目研究成果为提高SOFC电极微观结构的设计水平提供理论指导和技术支撑。

电极是组成固体氧化物燃料电池（SOFC）的关键部件之一，开展电极微观结构优化研究对于提高SOFC整体性能具有重要意义。本项目从SOFC电极X-ray三维重构出发，构建真实的三相电极微结构，并采用统计理论对电极微结构进行表征。建立了电极微观孔隙结构多组分气体传输的完整DGM模型、相场断裂模型和多场耦合数值模拟方法，研究了阳极微观孔隙结构内存在多重化学反应的气体传质机理过程，揭示了电极微观结构对气体传输、导电、传热、应力和断裂等性能的影响规律和多物理场耦合效应机理；建立了SOFC制备过程中的应力演化模型，揭示了非平整界面引起的电极力学失效机理，根据球颗粒随机堆积理论对电极参数进行优化。建立了完整结构的1-kW级电堆多场耦合模型，探究了电堆层间流量和电势差分配特性，揭示了电堆稳态和瞬态工作中存在的力学失效机理。建立了综合考虑电极抗应力和电性能的电极微观结构优化理论和方法，对阴阳极的三相微结构进行了优化。实验制备了低热膨胀系数失配的SOFC阴极材料。项目研究成果可为提高SOFC电极微观结构的设计水平提供理论指导和技术支撑。