In recent years, designing architectured electrodes with the goal of improving overall energy conversion efficiency has started [2, 3]. However, full leverage of such state-of-the-art procedures for designing engineered electrodes strongly depends on the employment of novel design tools. Among various advanced design alternatives, the attention of researchers in different disciplines of engineering has recently been drawn to topology optimization methods [4]. While topology optimization was originally applied to structural mechanics, it has since been expanded to more complicated systems with multiple physics, including heat and fluid. However, with only a few exceptions [5, 6], most topology optimization applications to electrochemical devices are limited to enhancing flow fields to boost reaction dispersion and diminish pressure drop. Moreover, previous research studies like [5] mainly used simplified two-dimensional isothermal models, which are far from reality. Therefore, these studies are incapable of providing a comprehensive insight into optimal spatial distribution of catalyst, electrolyte, and voids in a porous electrocatalyst layer.
In the present study, a three-dimensional, non-isothermal, multi-phase model is developed to simulate the performance of PEMFC. The presented model is then used to determine the optimal spatial distribution of the porous electrocatalyst layer constituents, including catalyst, electrolyte, and voids. While increasing the catalyst content in the PEMFC electrode could improve cell performance, its excessive use leads to a substantial increment of cost and oxygen transport resistance. This mass transport resistance problem is especially critical at high current density regions with a higher risk of flooding. Hence, in the present study, the optimization process is formulated as a constrained problem so as to obtain maximum output voltage under a constant total catalyst loading. The results show that in an optimal design, the volume fraction of catalyst and electrolyte should be higher in the region under the channel where there is a higher potential for current density production. At the same time, it is desired to increase the porosity in the region under the rib where oxygen delivery involves more resistance.
Acknowledgment
This work was supported by JSPS KAKENHI Grant Number 21H04540.
References
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