Comparative Investigation of Polyphenylene Sulfide Polymer-Graphite Bipolar Plates for Fuel Cell Application

Abstract

In this work two compression molded commercial polyphenylene sulfide (PPS) polymer-graphite composite bipolar plates (BPPs) with different amount of polymer binder material from two different manufacturers were employed for an analytical comparative investigation using physical and electrochemical analysis. Chemical stability of BPPs was investigated after storage in phosphoric acid. Corrosion resistance and electrochemical aging of the BPPs were studied by using linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in phosphoric acid. In order to characterize the difference in physical properties water contact angle measurement and through-plane electrical conductivity experiments were performed. The morphology of the BPPs surface was determined by scanning electron and confocal microscopy. The chemical composition was investigated by X-ray diffraction and energy dispersive X-ray spectroscopy, respectively. Comparison of BPPs revealed that the surface roughness and electrical conductivity is lower while acid uptake and hydrophilicity is higher for BPP with higher amount of PPS. Moreover, there was a trend of corrosion rate reducing for BPP with increased PPS content. This behaviour could be explained based on structure and electrical properties of the materials.