Modeling an ordered nanostructured cathode catalyst layer for proton exchange membrane fuel cells

Abstract

Modeling an ordered nanostructured cathode catalyst layer for proton exchange membrane fuel cells Hussain, M.M.; Song, D.; Liu, Z.-S.; Xie, Z.This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. abstract A 3D mathematical model of an ordered nanostructured cathode catalyst layer (CCL) has been developed for proton exchange membrane (PEM) fuel cells. In an ordered nanostructured CCL, carbon nanotubes (CNTs) are used as support material for Pt catalyst, upon which a thin layer of proton-conducting polymer (Nafion) is deposited, which are then aligned along the main transport direction (perpendicular to the membrane) of various species. The model considers all the relevant processes in different phases of an ordered nanostructured CCL. In addition, the effect of Knudsen diffusion is accounted in the model. The model can predict not only the performance of an ordered nanostructured CCL at various operating and design conditions but also can predict the distributions of various fields in different phases of an ordered nanostructured CCL. The predicted nanostructured CCL performance with estimated membrane overpotential is validated with measured data found in the literature, and a good agreement is obtained between the model prediction and measured result. Moreover, a parametric study is conducted to investigate the effect of key design parameters on the performance of an ordered nanostructured CCL. In the absence of liquid water, it is found that oxygen diffusion in the pore phase is not the limiting factor for the performance of an ordered nanostructured CCL, owing to its parallel gas pores and high porosity. However, the transport of dissolved oxygen through the Nafion phase has a significant effect on the performance of an ordered nanostructured CCL. Further, it is found that increasing the spacing between CNTs results in a considerable drop in the performance of an ordered nanostructured CCL at the base case conditions considered in the simulation.

Performance and degradation of Proton Exchange Membrane Fuel Cells: State of the art in modeling from atomistic to system scale

“…Moreover, these uniformly distributed and aligned carbon nanotubes electrodes are more resistant to electrochemical oxidation. Aligned carbon nanotubes have most recently been modeled by Hussain et al [167]. Once corrected by the membrane overpotential and the mixed-electrode potential, their 3D model is in good agreement with polarization curves from the literature.…”

3D Model of an Order-Structured Cathode Catalyst Layer with Vertically Aligned Carbon Nanotubes for PEM Fuel Cells under the Water Flooding Condition

“…To further improve the utilization of the Pt catalyst and the performance of VACNT CCL, it is necessary to optimize the parameters of the VACNT structure. According to the previous modeling research, the most important parameters are the spacing between VACNTs, the length of VACNTs, and the Nafion loading. , When these parameters are changed, other parameters including the Pt loading are fixed and thus the thickness of the Pt–Nafion subdomain is altered. Therefore, changing the spacing between VACNTs, the length of VACNTs and the thickness of the Nafion subdomain will not alter the active surface area of Pt, but proton and oxygen transport will be affected.…”

“…The models were amended by considering Knudsen diffusion in gas pores because the pores are very small . Then, a three-dimensional (3D) model was improved and the effects of the Nafion thickness, CNT length, and CNT spacing were analyzed . It is found that gaseous oxygen diffusion in the pore phase is not the limiting factor for the performance of the nanostructured catalyst layer in the absence of liquid water.…”

Advanced catalytic layer architectures for polymer electrolyte membrane fuel cells

“…Rao et al and Hussain et al simulated the influence of the thickness and the spacing between the VACNFs on the performance of the cathode . The results showed the importance of considering Knudsen diffusion when the distance between nanofibers becomes comparable to the mean free path of the gases, i.e.…”