The Resistive Properties of Proton Exchange Membrane Fuel Cells With Stainless Steel Bipolar Plates

In this research, electrochemical impedance spectroscopy is employed to monitor the resistance of a fuel cell during operation with different operating conditions and different materials for the bipolar plates. The operating condition variables are cell humidity, pure oxygen or air as oxidizer, and current density. Three groups of single cells were tested: a graphite cell, a stainless steel cell (treated and original), and a thin, small, treated stainless steel cell. A treated cell here means using an electrochemical treatment to improve bipolar plate anticorrosion capability. From the results, the ohmic resistance of a fully humidified treated stainless steel fuel cell is $0.28Ωcm2$⁠. Under the same operating conditions, the ohmic resistance of the graphite and the original fuel cell are each $0.1Ωcm2$ and that of the small treated cell is $0.3Ωcm2$⁠. Cell humidity has a greater influence on resistance than does the choice of oxidizer; furthermore, resistance variation due to humidity effects is more serious with air support. From the above results, fuel cells fundamental phenomenon such as ohmic resistance, charge transfer resistance, and mass transport resistance under different operating conditions could be evaluated.