Understanding Porous Transport Layer Structure-Property-Performance Relationships in PEM Water Electrolyzers

Abstract

Low temperature electrolysis (LTE) is a very promising technology to help with the decarbonization of the energy sector through the production of green hydrogen from renewable energy sources. The DOE has recently launched the first Energy Earthshot targeting the reduction of clean hydrogen cost by 80% to $1 per 1 kg H2 produced in 1 decade. To reach such ambitious targets the technology development needs to consider both capital expenditures (CAPEX) such as material and component costs and their lifetimes, as well as operational expenditures (OPEX) such as cell performance and efficiency. One component that touches on either expenditure is the porous transport layer (PTL). The PTL provides various key functions within an electrolysis cell/stack. It provides transport pathways for electrons, water and gas, and mechanical support for the membrane. Its interface with the catalyst layer is crucial with regards to the limitation of ohmic overpotentials, but also heat transport within the cell. PTLs are currently fabricated from sintered Ti materials that are required to be coated with a PGM material when operated with low loading catalyst layers. Multi-layer PTL materials may further improve cell performance and enable the thrifting of catalyst loadings and the utilization of thin membrane materials. This presentation will introduce the various functionalities of the PTL and highlight research and development efforts including those of DOE’s H2New Consortium and NREL. Specifically impacts of PTL morphology, PTL coatings, and PTL/catalyst layer interactions will be discussed.