In-Plane Transport in Water Electrolyzer Porous Transport Layers with Through Pores

Abstract

The mass transport in porous transport layers (PTLs) with pores exclusively in the through-plane direction was investigated using concurrent in operando X-ray radiography and electrochemical performance analysis. We observed via synchrotron X-ray imaging that through pores situated under the lands are inaccessible to liquid water. We thereby observed the limited in-plane mass transport that takes place in PTLs with pores exclusively in the through-plane direction. Additionally, a higher content of product gas was observed with the use of the PTL with through pores under both the channels and the lands (PTL Ch,L ) when compared to the PTL with through pores only under the channels (PTL Ch ). This oxygen gas accumulation behaviour corresponded to the higher mass transport overpotential of the PTL Ch,L compared to the PTL Ch . Finally, the limited in-plane mass transport in the PTL with through pores led to a relatively dehydrated catalyst layer, which was exhibited through higher ionic resistances as a function of increasing current density.