Periodic Report Summary 1 - IMPALA (IMprove PEMFC with Advanced water management and gas diffusion Layers for Automotive application)
Project Context and Objectives:
Overview
The purpose of IMPALA is to manufacture improved GDL to increase performance (up to 1 W/cm²) and durability of PEMFC for automotive applications. Two approaches will be followed: i) homogeneous GDL will be modified to ensure a better water management (formulation of the MPL, wettability, stability of the hydrophobic treatment, hydrophilic layers, and conductive additives). Most of these modifications should be transferable to industry. ii) more innovative non uniform GDL will be manufactured to adjust their local properties to the non-uniform local operating conditions of a PEMFC (gradients of porosity and of wettability, patterns of hole). This is a higher risk approach as some modifications could be difficult to transfer to industry but the improvements should be higher and lead to breakthrough GDL.
This technological work will be supported by a deep water management analysis combining the most advanced two-phase models (Pore Network Modelling) and the most advanced experimental diagnostics (liquid visualisation by X-Ray). This will allow having a much better understanding on water management and on the link between main properties of GDL (thickness, pore size and wettability distribution…) and their performance in PEMFC. This will ensure important scientific progress and provide recommendations for design.
The project is focused on standard automotive conditions but special attention will be paid to ensure the improvements will be valid for different stack design for back-up applications.
The consortium gathers the necessary international complementary leading expertise to reach the project targets: INPT: two-phase modelling, PSI: X-Ray visualisation, JRC: modelling and tests, CEA: performance modelling, tests and modification of GDL, DLR: characterization, SGL: manufacturing performing GDL, and NEDSTACK: stack tests for automotive and back-up application.
Main targets
• MEA Level 0 (M6): ~ 0.75 W/cm² at 1.5 A/cm² (BoL)
• MEA Level 1 (M18): ~ 0.9 W/cm² at 1.5 A/cm² (BoL)
• MEA Level 2 (M31): ~ 1.0 W/cm² at 1.5 A/cm² (BoL) with degradation rates comparable to or lower than reference MEA
These targets are defined for 25 cm² single cells for automotive application (80°C, RH 50%, 1.5 bara, Stoe 1.2 (A)/2 (C)); then improvements will be quantified for stack and back-up application.
In order to do so, a technological route has been defined, supported by a scientific route.
Technological route: produce new homogeneous and innovative structured GDL to increase performance and durability of MEA
• produce new GDL
o homogeneous GDL by improving transport properties of MPL, adding specific layers, improving hydrophobic treatment, and tuning specific MPL for anode and for cathode.
o innovative structured GDL by introducing gradients in the MPL (porosity, wettability, conductivities), and in the substrate (wettability, holes)
• with improved performance
o Increasing the power density (BoL) from roughly 0.8 W/cm² at 1.5 A/cm² to 1.0 W/cm² at 1.5 A/cm².
o Reducing degradation of MEA linked to water management and loss of hydrophobicity.
Scientific route: better understand water management in GDL and in MEA and propose design recommendations
• better understand water management in GDL
o Characterize one-phase and two-phase transport properties
o improve two phase Pore Network Modelling (condensation, structure, multi-layers)
• and in MEA during operation
o visualize two phase pattern during operation (3D X-Ray, optical)
o measure global and local performance of MEA
o improve performance models using PNM outputs to link local properties of GDL to performance in MEA
• and propose design recommendations
One major output of IMPALA will also be the extensive comparison between experiments and modelling by using 3D images of GDL to model one and two-phase transfer properties and liquid transfers that will be compared to ex-situ characterizations and in-situ 3D visualizations to better link local properties of GDL and performance of PEMFC.
Project Results:
Main targets
• MEA Level 0 (reference MEA) has been reached (with SGL 24BC) and even exceeded (~ 0.75 W/cm²)
• MEA Level 1 is considered as reached (~ 0.89 W/cm²) thanks to modifications of homogeneous GDL
Technological route: produce new homogeneous and innovative structured GDL to increase performance and durability of MEA
• Modifications of homogeneous GDL have been done: results show that the performance can be increased with new ink formulation of the MPL, conductive additives in the MPL and/or in the substrate, innovative chemical grafting (to modify hydrophobicity)
• First non-homogeneous structured GDL have been produced: preliminary results show no clear improvement of performance with laser ablation or hole patterns; gradients of MPL could be of interest; more work will be discussed before final conclusion
• Some reproducibility issues are to be solved in the manufacturing processes and durability is to be checked
• Tests on MEA Level 0 has been done at stack level as a basis to compare to future developments
Scientific route: better understand water management in GDL and in MEA and propose design recommendations
The water management in a PEFC is strongly determined by water (in gaseous and liquid) transport and saturation properties of the gas diffusion layer (GDL). Water management and in turn the cell performance can be improved by optimizing the water transport properties of the GDL. The optimization of GDL on the one hand requires careful analysis of the transport properties of the GDL materials.
• Numerous characterizations of GDL have started: one and two-phase transport properties, surface energy
• The structure of the dry GDL (fibres, binder and contained porosity), and MPL has been determined in 3D using XTM. The segmented structures will be used for accurate determination of the transport properties by modelling using the X-ray derived structures
• Two-phase Pore Network has been improved by including condensation, comparing to ex-situ two-phase experiments, analysing condensation/liquid injection scenario
• Ex-situ visualisation of liquid pattern in GDL has started and the corresponding capillary pressure curves will be used to compare to modelling
• In-operando experiments with X-Ray 3D liquid pattern have been measured. The complex image evaluation is still under development.
• Simulations with performance models have started and work has also started on the corresponding experiments to improve their electrochemical fitting, which is mandatory before using these models to propose design recommendations
Dissemination
Dissemination has started in different ways:
• a common workshop between the two projects IMPALA and IMPACT is under discussion in the frame of next FDFC conference (Toulouse, France, 02/2015)
• some publications have been performed:
o I. Biswas, P. Gazdzicki, M. Schulze, ECS Transactions 2013
o A. Lamibrac, J. Roth, F. Marone, F.N. Büchi, 2013 annual report Electrochemistry Laboratory, PSI,
• IMPALA project and first results have been presented:
o Hydrogen&Fuel Cells 2013, Vancouver
o GDCh Wissenschaftsforum 2013, Darmstadt
o ECS Meeting, San Francisco 2013
o Fuel Cell Seminar 2013, Columbus
o Materials and Technologies for Fuel Cells, Plzen, 2014
o 2014 DPG spring meeting, Dresden
o International Workshop Stack Testing 2014, Stuttgart
o Modval 11th Symposium, Winterthur
Address of the project public website
A web site has been created (http://www.impala-project.eu/) with a private area limited to the partners and a public one.
Potential Impact:
Based on structural characterisation, in-situ water imaging and modelling results, a better design concept of a GDL is expected which should be able to meet the MEA Level 2 power density requirements provided that the new formulations and materials could be implemented into a GDL in a reproducible way.
It shall also provide better scientific knowledge on water management, which is a key issue for performance and durability, and more predictable models to analyze the link between properties of GDL and performance of PEMFC and propose more reliable design of recommendations. The project will give a unique opportunity to compare most advanced modeling and diagnostics.
One major output of IMPALA will also be the extensive comparison between experiments and modelling by using 3D images of GDL to model one and two-phase transfer properties and liquid transfers in GDL and MEA that will be compared to ex-situ characterization, in-situ 3D visualizations, and performance results. This should help progressing on the link between properties of GDL and performance of PEMFC to make a step onto design tools.
These developments will contribute to the development and commercialization of PEMFC technology.
IMPALA shall provide opportunities to reduce cost of PEMFC for automotive and back up applications by manufacturing improved MEA with high power density. It will give the opportunity to promote materials and technologies developed by European industries and laboratories.
Up-to-date, all the targets planned are kept unchanged even if the final MEA Level 2 target (1W/cm²) is really challenging with the current materials.
List of Websites:
//www.impala-project.eu/
Overview
The purpose of IMPALA is to manufacture improved GDL to increase performance (up to 1 W/cm²) and durability of PEMFC for automotive applications. Two approaches will be followed: i) homogeneous GDL will be modified to ensure a better water management (formulation of the MPL, wettability, stability of the hydrophobic treatment, hydrophilic layers, and conductive additives). Most of these modifications should be transferable to industry. ii) more innovative non uniform GDL will be manufactured to adjust their local properties to the non-uniform local operating conditions of a PEMFC (gradients of porosity and of wettability, patterns of hole). This is a higher risk approach as some modifications could be difficult to transfer to industry but the improvements should be higher and lead to breakthrough GDL.
This technological work will be supported by a deep water management analysis combining the most advanced two-phase models (Pore Network Modelling) and the most advanced experimental diagnostics (liquid visualisation by X-Ray). This will allow having a much better understanding on water management and on the link between main properties of GDL (thickness, pore size and wettability distribution…) and their performance in PEMFC. This will ensure important scientific progress and provide recommendations for design.
The project is focused on standard automotive conditions but special attention will be paid to ensure the improvements will be valid for different stack design for back-up applications.
The consortium gathers the necessary international complementary leading expertise to reach the project targets: INPT: two-phase modelling, PSI: X-Ray visualisation, JRC: modelling and tests, CEA: performance modelling, tests and modification of GDL, DLR: characterization, SGL: manufacturing performing GDL, and NEDSTACK: stack tests for automotive and back-up application.
Main targets
• MEA Level 0 (M6): ~ 0.75 W/cm² at 1.5 A/cm² (BoL)
• MEA Level 1 (M18): ~ 0.9 W/cm² at 1.5 A/cm² (BoL)
• MEA Level 2 (M31): ~ 1.0 W/cm² at 1.5 A/cm² (BoL) with degradation rates comparable to or lower than reference MEA
These targets are defined for 25 cm² single cells for automotive application (80°C, RH 50%, 1.5 bara, Stoe 1.2 (A)/2 (C)); then improvements will be quantified for stack and back-up application.
In order to do so, a technological route has been defined, supported by a scientific route.
Technological route: produce new homogeneous and innovative structured GDL to increase performance and durability of MEA
• produce new GDL
o homogeneous GDL by improving transport properties of MPL, adding specific layers, improving hydrophobic treatment, and tuning specific MPL for anode and for cathode.
o innovative structured GDL by introducing gradients in the MPL (porosity, wettability, conductivities), and in the substrate (wettability, holes)
• with improved performance
o Increasing the power density (BoL) from roughly 0.8 W/cm² at 1.5 A/cm² to 1.0 W/cm² at 1.5 A/cm².
o Reducing degradation of MEA linked to water management and loss of hydrophobicity.
Scientific route: better understand water management in GDL and in MEA and propose design recommendations
• better understand water management in GDL
o Characterize one-phase and two-phase transport properties
o improve two phase Pore Network Modelling (condensation, structure, multi-layers)
• and in MEA during operation
o visualize two phase pattern during operation (3D X-Ray, optical)
o measure global and local performance of MEA
o improve performance models using PNM outputs to link local properties of GDL to performance in MEA
• and propose design recommendations
One major output of IMPALA will also be the extensive comparison between experiments and modelling by using 3D images of GDL to model one and two-phase transfer properties and liquid transfers that will be compared to ex-situ characterizations and in-situ 3D visualizations to better link local properties of GDL and performance of PEMFC.
Project Results:
Main targets
• MEA Level 0 (reference MEA) has been reached (with SGL 24BC) and even exceeded (~ 0.75 W/cm²)
• MEA Level 1 is considered as reached (~ 0.89 W/cm²) thanks to modifications of homogeneous GDL
Technological route: produce new homogeneous and innovative structured GDL to increase performance and durability of MEA
• Modifications of homogeneous GDL have been done: results show that the performance can be increased with new ink formulation of the MPL, conductive additives in the MPL and/or in the substrate, innovative chemical grafting (to modify hydrophobicity)
• First non-homogeneous structured GDL have been produced: preliminary results show no clear improvement of performance with laser ablation or hole patterns; gradients of MPL could be of interest; more work will be discussed before final conclusion
• Some reproducibility issues are to be solved in the manufacturing processes and durability is to be checked
• Tests on MEA Level 0 has been done at stack level as a basis to compare to future developments
Scientific route: better understand water management in GDL and in MEA and propose design recommendations
The water management in a PEFC is strongly determined by water (in gaseous and liquid) transport and saturation properties of the gas diffusion layer (GDL). Water management and in turn the cell performance can be improved by optimizing the water transport properties of the GDL. The optimization of GDL on the one hand requires careful analysis of the transport properties of the GDL materials.
• Numerous characterizations of GDL have started: one and two-phase transport properties, surface energy
• The structure of the dry GDL (fibres, binder and contained porosity), and MPL has been determined in 3D using XTM. The segmented structures will be used for accurate determination of the transport properties by modelling using the X-ray derived structures
• Two-phase Pore Network has been improved by including condensation, comparing to ex-situ two-phase experiments, analysing condensation/liquid injection scenario
• Ex-situ visualisation of liquid pattern in GDL has started and the corresponding capillary pressure curves will be used to compare to modelling
• In-operando experiments with X-Ray 3D liquid pattern have been measured. The complex image evaluation is still under development.
• Simulations with performance models have started and work has also started on the corresponding experiments to improve their electrochemical fitting, which is mandatory before using these models to propose design recommendations
Dissemination
Dissemination has started in different ways:
• a common workshop between the two projects IMPALA and IMPACT is under discussion in the frame of next FDFC conference (Toulouse, France, 02/2015)
• some publications have been performed:
o I. Biswas, P. Gazdzicki, M. Schulze, ECS Transactions 2013
o A. Lamibrac, J. Roth, F. Marone, F.N. Büchi, 2013 annual report Electrochemistry Laboratory, PSI,
• IMPALA project and first results have been presented:
o Hydrogen&Fuel Cells 2013, Vancouver
o GDCh Wissenschaftsforum 2013, Darmstadt
o ECS Meeting, San Francisco 2013
o Fuel Cell Seminar 2013, Columbus
o Materials and Technologies for Fuel Cells, Plzen, 2014
o 2014 DPG spring meeting, Dresden
o International Workshop Stack Testing 2014, Stuttgart
o Modval 11th Symposium, Winterthur
Address of the project public website
A web site has been created (http://www.impala-project.eu/) with a private area limited to the partners and a public one.
Potential Impact:
Based on structural characterisation, in-situ water imaging and modelling results, a better design concept of a GDL is expected which should be able to meet the MEA Level 2 power density requirements provided that the new formulations and materials could be implemented into a GDL in a reproducible way.
It shall also provide better scientific knowledge on water management, which is a key issue for performance and durability, and more predictable models to analyze the link between properties of GDL and performance of PEMFC and propose more reliable design of recommendations. The project will give a unique opportunity to compare most advanced modeling and diagnostics.
One major output of IMPALA will also be the extensive comparison between experiments and modelling by using 3D images of GDL to model one and two-phase transfer properties and liquid transfers in GDL and MEA that will be compared to ex-situ characterization, in-situ 3D visualizations, and performance results. This should help progressing on the link between properties of GDL and performance of PEMFC to make a step onto design tools.
These developments will contribute to the development and commercialization of PEMFC technology.
IMPALA shall provide opportunities to reduce cost of PEMFC for automotive and back up applications by manufacturing improved MEA with high power density. It will give the opportunity to promote materials and technologies developed by European industries and laboratories.
Up-to-date, all the targets planned are kept unchanged even if the final MEA Level 2 target (1W/cm²) is really challenging with the current materials.
List of Websites:
//www.impala-project.eu/