Contact resistance measurement methods for PEM fuel cell bipolar plates and power terminals

• Published in: Journal of power sources Vol. 555; p. 232341
• Main Authors: Mølmen, Live, Fast, Lars, Lundblad, Anders, Eriksson, Peter, Leisner, Peter
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2023
• Subjects: Aluminium; Binary alloys; Bipolar-plates; Contact resistance; Current voltage characteristics; Durability; Electric contacts; Electric resistance measurement; Electrical contact resistance; Electrical contacts; GDL; Keys parameters; Measurement methods; NiP; NiSn; PEM fuel cell; PEMFC; Polyelectrolytes; Power terminals; Proton exchange membrane fuel cells (PEMFC); Resistance measurement; Screw connections; Screws; Uncertainty analysis; PEMFC; Aluminium; NiSn; NiP; GDL; Electrical contact resistance
• ISSN: 0378-7753; 1873-2755; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.232341

The electrical contact resistance is a key parameter for optimising both the bipolar plate of the polymer electrolyte membrane fuel cell (PEMFC) and the electrical contact of the power terminal of the stack. The contact resistance is affected by the conductivity, roughness, and hardness of the two contacting surfaces. Here, new, application-specific contact resistance measurement methods are proposed for both the stack power terminal, and the bipolar plate. The proposed methods are compared to methods from references as well as standards, and it is concluded that the uncertainty of the measurements can be reduced by changing the measurement setup, and that the influence of probe resistance on measurement results can be eliminated. Furthermore, the effect of different accelerated durability tests on the contact resistance of the power terminal is examined both on test coupons and on a prototype screw connection with an electroless NiP and an electroplated NiSn coatings. As expected, the NiSn coupons gives lower contact resistance after ageing as compared to the NiP. However, the increase in contact resistance seen on coupons after ageing is not observed on the prototype screw connection.
•The proposed method for bipolar plates is simplified and reduces the uncertainty.•The proposed method for power terminals measures the application resistance.•Atmospheric durability is tested for the power terminal on coupons and a prototype.•Electroless NiP and electroplated NiSn on Al are compared.