固体氧化物电解池梯度复合电极物质输运特性研究

The performance of a solid oxide electrolysis cell (SOEC) is dramatically affected by the performance of the electrodes. The application of the multi-layer composite electrodes with grading particle size or grading porosity may effectively reduce the effects of the electrode degradation on the performance of the SOEC. Mathematical modeling of the substance transportation characteristics in the composite electrodes is of significant for the optimum design of the microstructure of the electrodes. . By employing mathematical modeling tool, the present project will establish a model of the composite electrode with grading particle size or grading porosity. The controlling equations for the electronic/ionic charge transfer and electrochemical reactions are formulated and solved, from which the effects of grading particle size or grading porosity on the electrode polarization are discussed. Furthermore, the models of proton-conducting SOEC with grading particle size or grading porosity are established, mathematical expressions for describing the mass transfer and energy transfer in the composite porous electrodes will be given, and consequently, the transportation characteristics of the multi-components in the composite electrodes and the corresponding irreversibilities can be discussed and obtained, respectively. The effects of the electrode microstructure parameters and the operating conditions on the transportation characteristics will be revealed. The present project can provide some theoretical basis for optimum design and operation of SOEC.

固体氧化物电解池(SOEC)的性能受电极性能的严重影响。采用多层的粒径上或孔隙率分布上具有一定梯度的复合电极新结构可有效降低电极衰减对电解池性能的影响。数学模拟SOEC梯度复合电极内物质输运特性对促进电极微结构优化设计有重要意义。. 本项目拟采用数学模拟方法，建立粒径梯度、孔隙率梯度的复合电极模型，应用几何学和统计学理论，建立并求解电荷传输的控制方程及电化学反应的控制方程，探索粒径梯度及孔隙率梯度对阴阳两极极化损耗的影响。在此基础上，建立梯度复合电极的质子传导型固体氧化物电解池模型，对电解池多孔梯度复合电极内发生的物理、化学过程如质量传输、能量传递等过程进行数学定量表述。应用数值模拟方法，模拟多组元反应物质在多孔电极的传输行为及相关不可逆损耗，探索复合电极微结构和各工作条件对电极内物质扩散、渗透等输运特性的影响，为电极微结构优化设计及电池的优化运行提供理论参考。

固体氧化物电解池（SOEC）在高温水解制氢及二氧化碳降解等方面有着广泛的应用前景，其性能受电极结构的严重影响，探索粒径梯度及空隙率梯度对阴阳两级极化损耗乃至SOEC性能的影响具有重要的科学意义和应用价值。我们采用平行孔电极模型数学上描述了多组元反应物/生成物在多孔电极的物理、化学反应，并描述了反应过程当中产生的不可逆损耗。研究表明，复合电极微结构和工作条件对复合电极内物质输运有重要影响，进而影响SOEC的整体性能。以质子传导型SOEC在太阳能降解二氧化碳中的应用为例，详细说明了SOEC的电极微结构及工作条件如何影响SOEC的热力学-电化学特性，据此提出若干能提高SOEC能量转化效率的新系统构型。