Molecular dynamics simulation of ion dynamics within SPEEK polymer electrolyte of PEM Fuel Cells

Abstract

Proton transport property is studied by modelling the intermolecular pair correlation functions of the proton ion with the electrode and the electrolyte of a polymer electrolyte fuel cell (PEMFC) by using Materials-Studio and then applying molecular dynamics simulation. A stable structure of the novel electrode design is obtained using density functional theory. When the polymer electrolyte is assumed as anhydrous, the efficiency of the proton transport increases. Analysis of the proton coordination numbers shows that more protons are found in the region of oxygen than sulfur atoms of the Sulfonic acid Ether Ester Ketone~(SEEK) electrolyte. The proton conductivity values are increased with including interaction effects from electrode compared to without. At a temperature of 333 K, these values of ion conductivity are $7.69 \times 10^{5} \hspace{1mm}\mathrm{S \hspace{1mm}cm^{-1}}$ and $4.28 \times 10^{5} \hspace{1mm}\mathrm{S \hspace{1mm}cm^{-1}}$, respectively, with and without. The network of the hydrogen bond is the path to transport of protons via the processes of hydrogen bond creating and breaking. The values of highest peaks in the radial distribution function ($g(r)$) calculations appear to fall in the hydrogen bond formation region. Thus, it looks that a combination of Pd$\rm_{3}$Ag as an electrode and unhydrated SEEK as an electrolyte could make up for a cost effective components of new design PEMFC.