Optimizing the PTFE wetproofing of nickel porous transport layers for anion exchange membrane water electrolyzers

Wetproofing is the process of applying a surface treatment to control the behavior of water. In fuel cell and electrolyzer applications, wetproofing of carbon-based diffusion layers is typically accomplished through the addition of polytetrafluoroethylene (PTFE) polymer. Unfortunately, at the anion exchange membrane electrolyzer (AEMEL) anode, carbon cannot be used, and nickel-based porous transport layers (PTLs) have become common. Due to differences in material density, hydrophilicity/hydrophobicity and structure, it is presently unknown how much PTFE should be added, if any, although it is believed that some level of wetproofing of Ni PTLs will be helpful for performance and durability. In this work, the effects of adding PTFE wetproofing to Ni anode PTLs are understood through a combination of microscopy, cell polarization measurements and steady-state measurements. This paper provides both a reliable method for wetproofing the PTLs as well as an optimum PTFE loading that can be used to design high performance PTLs for commercial AEMELs. • PTFE wetproofing is added to Ni anode PTLs in AEM electrolyzers. • Performance and durability are studies over wide PTFE loading. • Simple, reliable method for wetproofing the PTLs is reported. • Optimum PTFE loading is reported that can be used for commercial PTL manufacturing.