Periodic Reporting for period 2 - CAMELOT (UNDERSTANDING CHARGE, MASS AND HEAT TRANSFER IN FUEL CELLS FOR TRANSPORT APPLICATIONS)
Période du rapport: 2022-07-01 au 2023-12-31
Fuel cell technology is advancing rapidly, providing energy saving solutions in a wide range of applications including transport and mobility. However, there are limitations in fuel cell membrane electrode assemblies (MEA, the core component in the electrochemical reaction) that must be overcome in order to improve performance. The EU-funded CAMELOT project is a consortium of research institutes and universities, MEA suppliers and transport original equipment manufacturers (OEMs) that aims to investigate ultra-thin and ultra-low loading layers required by the future MEAs. The project will combine numerical modelling with innovative in situ characterisation to develop a scientific understanding of the performance limitations in state-of-art (SoA) and beyond SoA MEAs. The overall objective of CAMELOT is thus to improve the power density of fuel cells through understanding of the limitations. This will be achieved through 1) diagnosis of transport properties in SoA and beyond SoA materials, 2) extension of a leading open source model to enable accurate simulation of SoA MEAs using automotive single repeat unit (SRU) hardware, 3) produce MEAs with potential to enable disruptive performance increases and to validate the open-source model for beyond SOA MEAs, and 4) propose new beyond SoA MEA designs in automotive compatible geometries that address SoA performance limitations and provide simulation tools that guide rational development of new MEA concepts.
The open-source FAST-FC model was originally developed as part of the DOE FC-Apollo project. The model will, as part of CAMELOT, be updated with a more robust and mechanistic liquid transport description for the MEA components and improved description of water transport within the ionomeric materials. Characterisation parameters and data from testing in screener cell and SRU level will be used to validate the model . The improved model will then be used to simulate SoA MEAs in order to extract theoretical understanding of performance limitations. From this knowledge, development of thin, ultra-low loaded catalyst layer and membrane designs will be proposed and prototyped using new production techniques to produce beyond SoA materials. These MEAs will feature gradients in X-Y-Z layers. Extensive in situ performance and ex situ characterisation will again be applied to quantify transport limitations and to validate the FAST-FC model for beyond SoA MEAs. The validated model will then be used to predict how the different designs will perform in automotive SRU hardware and provide recommendations for future development of MEAs.
Improvement of power density in PEM is important for reducing the power train thermal envelope. Cost reduction is realised through reduced critical raw material use and improved durability.
The update of an open-source model for characterisation of MEA performance is an important contribution to the fuel cell community.
The open-source FAST-FC model was originally developed as part of the DOE FC-Apollo project. The model will, as part of CAMELOT, be updated with a more robust and mechanistic liquid transport description for the MEA components and improved description of water transport within the ionomeric materials. Characterisation parameters and data from testing in screener cell and SRU level will be used to validate the model . The improved model will then be used to simulate SoA MEAs in order to extract theoretical understanding of performance limitations. From this knowledge, development of thin, ultra-low loaded catalyst layer and membrane designs will be proposed and prototyped using new production techniques to produce beyond SoA materials. These MEAs will feature gradients in X-Y-Z layers. Extensive in situ performance and ex situ characterisation will again be applied to quantify transport limitations and to validate the FAST-FC model for beyond SoA MEAs. The validated model will then be used to predict how the different designs will perform in automotive SRU hardware and provide recommendations for future development of MEAs.
Improvement of power density in PEM is important for reducing the power train thermal envelope. Cost reduction is realised through reduced critical raw material use and improved durability.
The update of an open-source model for characterisation of MEA performance is an important contribution to the fuel cell community.
At the beginning of the project, improvement of the implementation of gaseous water transport in the FAST-FC model was started. Literature was reviewed, and it was found that published data showed a large value span for key parameters. It was found that specific project characterisation was required in order to have representativeness for thin layers. The final model describes water transport through chemical potential gradient, liquid water pressure gradient and electroosmotic drag. The implemented model was shown to describe water uptake and release in dynamic vapor sorption experiments well.
An extensive characterisation package was established at month 6 of the project, this was important for the verification of the production of thin layers in the project. Characterisation of the SoA materials was performed and eventually progressed towards characterisation of new materials. In addition to electrochemical properties (e.g. voltage loss breakdown), with uncertainty limits, physical parameters (e.g water uptake), SEM imaging of thin membrane cross sections and graded layers with varying ionomer content (µXRF sulfur mapping) show that characterisation methods of materials is well established and ready to study the new layers developed within the project.
For the development of layers, several manufacturing techniques have been explored. For 10 and 8 µm membranes, focus has been on production consistency with respect to layer quality consistency. For additive layer manufacturing, manufacture of layers as thin as 6.5 µm has been achieved. For ultra-low loaded cathode, MEA performance data has been assessed for different catalysts. Understanding has been gained for disruptive deposition methods and work towards optimisation of spray coated layers. Further, deposition and performance assessment of initial layers with X-Y gradient has been completed.
Model validation work has been started through testing of MEAs with wet/dry and hot/cold operation.
An extensive characterisation package was established at month 6 of the project, this was important for the verification of the production of thin layers in the project. Characterisation of the SoA materials was performed and eventually progressed towards characterisation of new materials. In addition to electrochemical properties (e.g. voltage loss breakdown), with uncertainty limits, physical parameters (e.g water uptake), SEM imaging of thin membrane cross sections and graded layers with varying ionomer content (µXRF sulfur mapping) show that characterisation methods of materials is well established and ready to study the new layers developed within the project.
For the development of layers, several manufacturing techniques have been explored. For 10 and 8 µm membranes, focus has been on production consistency with respect to layer quality consistency. For additive layer manufacturing, manufacture of layers as thin as 6.5 µm has been achieved. For ultra-low loaded cathode, MEA performance data has been assessed for different catalysts. Understanding has been gained for disruptive deposition methods and work towards optimisation of spray coated layers. Further, deposition and performance assessment of initial layers with X-Y gradient has been completed.
Model validation work has been started through testing of MEAs with wet/dry and hot/cold operation.
The project ambition of producing ultra-thin reinforced membranes of < 10 µm has been achieved. While consistency in 8 µm layer quality is being optimised, additive layer manufacturing has succeeded in producing layers at 6.5 µm. For the characterisation work, uncertainty in estimates have been established through repeated measurements. These data will be further used to establish knowledge about statistical distribution of component properties.
With parameterisation of the model completed for SOA materials, the knowledge gained on performance limitations will be used to guide the thin layer and ultra-low loading component development further. Further development of the FAST-FC model will be done with transport of liquid water in MEA pore structure and flow fields. Characterisation will be performed on the beyond SOA developed components and further validation of the model will be performed in order to be able to predict performance limitations for alternative materials and design. Characterisation techniques will also be further developed to provide beyond SOA FIB-SEM characterisation of layers and statistical distributions of characterisation parameters.
The final output of the project is the publication of the FAST-FC model on GitHub. This open-source tool based on OpenFOAM will be a valuable tool to the fuel cell community for characterisation component performance and prediction of performance as function of material and design.
The project as whole has for objective to provide understanding for disruptive performance gains through production of thinner layers. In addition to making increased power density available for transport applications, cost reduction can also be realised through lower used of catalyst, ionomer and through improved durability.
With parameterisation of the model completed for SOA materials, the knowledge gained on performance limitations will be used to guide the thin layer and ultra-low loading component development further. Further development of the FAST-FC model will be done with transport of liquid water in MEA pore structure and flow fields. Characterisation will be performed on the beyond SOA developed components and further validation of the model will be performed in order to be able to predict performance limitations for alternative materials and design. Characterisation techniques will also be further developed to provide beyond SOA FIB-SEM characterisation of layers and statistical distributions of characterisation parameters.
The final output of the project is the publication of the FAST-FC model on GitHub. This open-source tool based on OpenFOAM will be a valuable tool to the fuel cell community for characterisation component performance and prediction of performance as function of material and design.
The project as whole has for objective to provide understanding for disruptive performance gains through production of thinner layers. In addition to making increased power density available for transport applications, cost reduction can also be realised through lower used of catalyst, ionomer and through improved durability.