Public Abstract: The aim of this work was to conduct testing of the HIGHLANDER baseline CCM (catalyst coated membrane) across a range of diagnostic tests including performance, catalyst accelerated stress tests (AST) and membrane accelerated stress tests, and to develop and apply a LPT (load profile test) to assess the degradation of the HIGHLANDER baseline CCM.
Also included in this work was the evaluation of new catalyst materials and the initial assessment of Solvay ionomer materials into the catalyst layers to progress the design towards the project target KPIs (key performance indicators) of >1.2 W/cm2 at 0.65 V, <0.3 g PGM (platinum group metals)/kW and a projected lifetime of 20,000 hrs.
Public Abstract: The aim of the work carried out for this report was to understand whether replacing a single cathode layer with a cathode bilayer (in the XY or Z gradient directions) in the HIGHLANDER membrane electrode assemblies (MEAs) would improve performance when compared to single cathode layer results. The XY and Z-gradient studies were conducted separately. The inks were made and coated at lab scale using slot-die coating equipment. The MEAs were tested under a performance protocol to assess the performance for a range of current densities under both dry and wet conditions (30% RH and 100% RH). This protocol was closely based on the diagnostics used in the HIGHLANDER LPT cycle outlined in D6.1, so performance was comparable with other material developments within this work package. No improvements were seen for XY gradient layers and very minimal benefits were seen for Z-gradient compositions. The Z-gradient results indicated that the layers acted largely as single layers overall within the ranges investigated in the study. Due to the coating method used, interactions were likely occurring between the layers, which may have impacted the results.
Public Abstract: This report assesses the major developments and concepts for performance improvement against a matrix for performance, volume manufacture viability, cost and applicability to other market segment applications.
Grading the cathode catalyst layer in the X-Y and Z dimensions was assessed with some potential identified especially with grading the layer through its thickness (Z-plane) although initial estimates suggest relatively small benefits compared to further material optimisations so this will likely be most applicable to mature product optimisation.
A catalyst recommended by Work Package 3 (Catalyst X) has shown significant performance benefits over existing state-of-the-art catalysts, allowing a halving of PGM loading whilst maintaining performance and still maintaining a projected lifetime greater than 20,000 h in accordance with the project target.
Advanced membranes incorporating electrospun nanofibre PBIX (polybenzimidazole type) reinforcements and a supported chemical stabilisation additive showed excellent durability and performance .