MPL coating procedure

The porous transport layer (PTL) is one the key components in variety of gas evolving electrochemical conversion technologies from fuel cells to carbon dioxide reduction and electrolyzers. The PTL has several purposes in electrolyzers, including thermal and electrical conduction, mechanical support, pathways for delivery of reactant liquid water to the catalyst layer, and removal of gaseous phase from the reaction sites to the outlet. The importance of the PTL is shown in a number of previous studies for electrolyzers. Multifunctional PTL was developed by introducing Nickel-based micro porous layers (MPLs) on the top of stainless-steel PTL substrates using vacuum plasma spraying technique and tested as a gas diffusion layer in AEMWE. The Ni-based MPL coated PTLs were characterized by SEM, EDX and XRD and with electrolyser cell testing. This deliverable is to report about the development of improved PTL for NEWELY AEMWE cells for operation in pure water and dilute KOH solution and it reports about the finally selected PTLs for the NEWELY stack.

Optimized Plasma-coating of porous Nickel as microporous layer on multilayer stainless steel PTLs were demonstrated to improve performance in both cells operated in pure water as well as 0.1 M KOH solution for Catalyst-Coated-Membrane (CCM) electrodes.

As the project moved to Catalyst-Coated-Substrate (CCS) electrodes an option how to realize MPL coating on market-available stainless-steel PTLs of the thickness as required for the NEWELY cell was realized, however, the performance in the cell could not be evaluated due to time limitations.

Finally, the NEWELY stack is equipped with CCS electrodes supported on commercial stainless steel felts and carbon papers and the PTLs are commercial stainless steel multilayer filter-grids and porous graphite.