Plasma treatment of the carbon fiber bipolar plate for PEM fuel cell

Abstract

A Polymer Electrolyte Membrane Fuel Cell or Proton Exchange Membrane (PEM) fuel cell stack is composed of a Gas Diffusion Layer (GDL), an Membrane Electrode Assembly (MEA), and bipolar plates. The electrical resistance of the bipolar plates for a PEM fuel cell should be very low, so that the electricity generated in the fuel cell is conducted through the bipolar plates with minimum electrical loss. In this study, a plasma etching treatment was developed to decrease the contact resistance between a GDL and continuous-carbon/epoxy composite bipolar plate. The treatment removes the resin-rich layer of the composite surface, which is the source of the majority of the electrical resistance of the bipolar plate. The optimum plasma treatment condition was determined by calculating the resin etching depth, taking into consideration the carbon fiber dimensions of the GDL and the continuous-carbon/epoxy composite bipolar plate. Scanning Electron Microscopy (SEM) analysis was performed on the surface of the composite bipolar plate for each variation of plasma surface treatment. In addition, the tensile strength and the electrical resistance (in the through-thickness direction) of the composite bipolar plate were measured for the different plasma surface treatment conditions.