Abstract
Melt processing is one of the essential technologies for the mass production of polymer electrolyte membranes (PEM) at low cost. Azoles have been widely used in PEM to improve their conductivity at a relatively low humidity and recently as bifunctional additives in a melt blowing processing for PEM mass production. In this work, we attempted to assess the effect of 1, 2, 4-triazole additive in membranes and in catalyst layers on PEM fuel cell conditioning. Various characterization tools including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and conditioning with constant current were applied to diagnose the temporary electrochemical reaction effect and the permanent performance loss caused by the triazole additives. It was found that triazole additives in membranes could migrate into the catalyst layers and significantly affect the open circuit voltage (OCV) and the conditioning. The effect could be partially or completely removed/cleaned either through longer conditioning time or via CV cycling, which depends on the amount of additives remaining in the membrane. The findings provide valuable scientific insights on the relevance of post treatment steps during membrane production and overcoming fuel cell contamination issues due to residual additive in the membranes and understanding the quality control needed for fuel cell membranes by melt blowing processing.
Highlights
Proton exchange membrane fuel cell (PEMFC) technology has been widely considered as the revolution in renewable energy due to its high theoretical energy efficiency and zero carbon emissions at the point of use [1]
The lower open circuit voltage (OCV) phenomena could be explained by the contamination of the catalyst layers by the 1, 2, 4-triazole additive, as it likely migrated from the membrane into the catalyst layers, leading to a decrease in OCV in the first few hours
The 1, 2, 4-triazole contaminated membrane was tested under OCV conditions and 1, 2, 4-triazole contaminated cathode Gas diffusion electrode (GDE) were investigated under fuel cell conditioning conditions
Summary
Proton exchange membrane fuel cell (PEMFC) technology has been widely considered as the revolution in renewable energy due to its high theoretical energy efficiency and zero carbon emissions at the point of use [1]. The azole family compounds such as 1, 2, 4-triazole, imidazole and benzimidazole have been widely used as potential bifunctional additives in a melt blowing processing [5]. They act as sulfonic acid groups (-SO3 H) protection and a melt processing aid to assist proton conduction by Grotthus mechanism under anhydrous/high temperature conditions [6,7,8].
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