Boosting solid oxide electrolyzer performance by fine tuning the microstructure of electrodes – Preliminary study

Abstract

This paper addresses the concept of adjusting the microstructure of the supports of solid oxide electrolyzers in order to boost performance. While several earlier studies focused on maximizing performance, reducing degradation, adjusting operating conditions and introducing new materials or designs of electrolysis stack, the current study addresses potential improvement of the cell by fine tuning the microstructure without any major redesign of existing cells. In the proposed approach, the study combined numerical simulations with definition of the model, which can aid in predicting the performance of a cell with adjusted porosity of the electrode support, and preparation of modified cells with alternative pore forming agents and two alternative sintering temperature levels. Supports of solid oxide cells were sintered at 1350 and 1400 °C with pore former content of 25–35%. This resulted in the porosity of supports being in the range of 47–54%. Cells with 10Sc1CeSZ and 8YSZ electrolytes were investigated in operando.The proposed approach makes it possible to quantitatively and qualitatively assess the potential gain when the reference cell is slightly modified, according to guidelines obtained from the model. It was found that the proposed method to fine tune the microstructure can result in improved performance, with a clear indication that adjusting the sintering temperature has a stronger effect on the microstructure of the support than increasing the pore forming agent.