Process Based Large Scale Molecular Dynamic Simulation of a Fuel Cell Catalyst Layer

Abstract

In this paper, a large scale molecular dynamic method for reconstruction of the catalyst layers (CLs) in proton exchange membrane fuel cells is developed as a systematic technique to provide an insight into the self-organized phenomena and the microscopic structure. The proposed Coarse-Grained (CG) method is developed and applied to the step formation process, which follows the preparation of the catalyst-coated membranes (CCMs). The fabrication process is mimicked and evaluated in details with consideration of the interactions of material components at a large scale. By choosing three sizes of the unit box, the relevant configurations of the equilibrium states are compared and analyzed. Furthermore, the primary pores of 2-10 nm in the agglomerates mainly consist of the channel space, which acts as the large networks and could be filled with liquid water. Moreover, various physical parameters are predicted and evaluated for four cases. The active Pt surface areas are also calculated by the current model, and then compared with the experimental data available in the literature. Finally, the pair correlation functions are employed to 2 predict the distributions and hydrophobic properties of the components, providing the information on phase segregation and microscopic structure of the CLs.

Synergetic Structural Transformation of Pt Electrocatalyst into Advanced 3D Architectures for Hydrogen Fuel Cells

“…In search of a higher electrocatalytic surface area, Xiao et al proposed a coarse‐grained method for reconstruction of microscopic Pt catalyst structures while considering Pt/C fractions, Nafion ionomers, and substantial water content. [ 134 ] Through large‐scale MD simulations, three target box sizes were investigated, and the volume of the pores and active Pt surface areas were evaluated and compared with experimental data. During the experimental validation, the arrangement of the corresponding catalyst layers was reconstructed within a 50 × 50 × 50 nm 3 volume.…”

Method to improve catalyst layer model for modelling proton exchange membrane fuel cell

“…During manufacturing, the carbon grains tend to aggregate, forming porous agglomerates [6] with their outer surfaces coated by a thin ionomer film [7,8]. As such, the catalyst layer has a bi-mode pore structure in which the pores inside the agglomerates (intra-agglomerate pores) are much smaller than the pores between the agglomerates (inter-agglomerate pores).…”

An integrated photonic-diffusion model for holographic sensors in polymeric matrices

“…Extensions of these models account for swelling, consider microscopic (kinetic) and mesoscopic (thermodynamic) levels, energy of mixing, molecular polymer structure conformations, and interfacial interactions [1][2][3]15]. There are certainly other works that further extend these models to consider conformations and deformations [16,17], or even to molecular dynamics simulations for transport processes but in other type of systems [18]. In this work, diffusion, swelling, mixing, and changes in optical diffraction are discussed as elements of an integrated theoretical model.…”