The fabrication and characteristics of electroless nickel and immersion Au-polytetrafluoroethylene composite coating on aluminum alloy 5052 as bipolar plate

In this work, a method to produce a hydrophobic Au-PTFE/Ni-P multilayer coating on Al-alloy substrate for an application in bipolar plates (BPPs) is described. This method involves electroless nickel on an untreated Al-alloy 5052, onto which gold and PTFE particles are subsequently co-deposited by an immersion technique. The effect of incorporation of PTFE particles on contact angle, interfacial contact resistance, corrosion resistance, and single cell performance of Au-PTFE/Ni-P coated Al-alloy BPPs are investigated. The images of scanning electron microscope show that the PTFE particles are homogeneously distributed in the Au matrix. Au-PTFE/Ni-P coating can effectively prevent the Al-alloy from corrosion. In addition, the contact resistance of Au-PTFE/Ni-P coating is higher than that of Au/Ni-P coating as a result of the presence of PTFE particles with the poor electrical conductivity. The contact angle of the Au-PTFE/Ni-P coating with water is 116.9°, which is much bigger than that of the Au/Ni-P coating (23.2°). The hydrophobic characteristic of the Au-PTFE/Ni-P coated bipolar plates facilitates the water management during the fuel cell operation. It results in the fuel cell with Au-PTFE/Ni-P coated bipolar plates has better performance than that with Au/Ni-P coated bipolar plates in the beginning and after 300 h operation.