Development and Analysis of an Innovative Flat-Metal Separator Integrating the GDL with Gas-Flow Channels as PEFC Components

Abstract

The gas diffusion layer (GDL) plus separator in the polymer electrolyte fuel cell contributes more than 1/3 to the stack cost, even at the mass production stage. Therefore, we have taken on the challenge to develop a new, integrated concept for these crucial components, based on intelligent application of low-cost technologies and, most importantly, uniform transport of reactant and product over the whole catalyst layer via forced cross-flow between neighboring interdigitated channels formed in the GDL. This new design concept promises to significantly lower cost, as well as improving performance and durability. Specifically, the design incorporates a corrosion-resistant flat-metal separator (FMS) with a thin carbon/resin coating, and a low-cost GDL, consisting of short carbon fibers (CFs) bonded with resin, forming gas-flow channels whose manufacture should be compatible with mass-production. At the optimized FMS + GDL, we have achieved 5.7 mΩ/cm2 contact-resistance and complete immunity to corrosion over 4,000 h in 0.1 M H2SO4 solution at 90°C. By combining various CFs and resins, the gas-diffusivity, electrical resistance and mechanical strength have been balanced and are sufficient for GDL application. A limiting current of 3.3 A/cm2 in a single cell has been achieved under pure H2 and140 kPa air at 80°C.