On the contact resistance between the anode and the porous transport layer in a proton exchange membrane water electrolyzer

The contact resistance between the anode catalyst layer and the titanium (Ti)-based porous transport layer (PTL) of a proton exchange membrane water electrolyzer (PEMWE) can limit the efficiency of the system and its durability. Generally, the PTL side in contact with the anode is coated with a precious metal, such as platinum. This results in an increased overall cost of the system. Here, we report on the influence of various metal coatings (400 nm coatings of platinum and gold; 2, 10, 400 nm coatings of iridium) on the beginning of life performance and on the durability of a PEMWE device. The durability tests included varying the voltage between 1.5 and 2.2V and between 0 and 2.2V with a total test duration of 510 h by sample). The best beginning of life performances are obtained with a platinum coating but the best durability during start-stop events is obtained with a 10 nm iridium coating (representing less than 2% of the amount of iridium present in the system). The influence of the clamping stress is also evaluated. Whatever the nature of the coating, the electrical contact resistance decreases with an increase in the clamping stress and depends on the clamping history.