Effects of Bipolar Plate Material and Impurities in Reactant Gases on PEM Fuel Cell Performance

Abstract

Biomass to biofuels production technologies are promising to reduce CO2 emissions. Complementing the fuel-production technologies is improvement in their end use, wherein efforts are underway to maximize fuel cell efficiency. In the polymer electrolyte membrane (PEM) fuel cell research and development (R&D), the metallic bipolar plate concept looks promising, but issues such as cost, corrosion resistance, interfacial contact resistance (ICR), and reactant gases impurities still need to be resolved. Of these, bipolar plate material and impurities in oxygen or hydrogen extracted from biomass gasification can have considerable influence on fuel cell performance. In this paper, measurements of the ICR between the gas diffusion layer (GDL) and a number of bipolar plate materials were obtained and analyzed. The ICR data showed a significant effect on the electric power output of the fuel cell. Additionally, typical impurities in oxygen gas were found to have an adverse effect on throughput of the fuel cell due to possible poisoning of the catalyst, the electrolyte, and/or the ionomer membrane. It was noted that the damage caused by these impurities could be permanent or reversible, depending on the type of impurity. X-ray diffraction (XRD) and other characteristics of both fresh and used samples of the membrane electrode assembly (MEA) in a PEM fuel cell after 1000 h of operation in a single hydrogen fuel cell are also reported to understand the underlying chemistry of the working metallic bipolar plates in a PEM fuel cell. Last, minimal loss of metals, established through the byproduct water analysis, showed prolonged performance of the fuel cell under operating conditions. Such a robust fuel cell when operating with biomass-derived biofuel could result in better utilization of biomass feedstocks when the cradle-to-grave energy efficiency is considered. This will help the biofuel industry to grow at a faster pace to commercialization.