Periodic Reporting for period 2 - NIMPHEA (Next generation of improved High Temperature Membrane Electrode Assembly for Aviation)
Reporting period: 2024-07-01 to 2025-06-30
H2-based fuel cell systems (FCs) are a promising solution to power aircrafts without emitting CO2 or NOx and thus have the potential to strongly reduce aviation emissions and pave the way to climate neutrality. Embedded in aircrafts, FCs can supply non-propulsive and propulsive energy without pollutant emission, reduced noise emission and attractive energy efficiency.
The Low Temperature Proton Exchange Membrane (LT-PEM) technology (incl. Membrane Electrode Assembly - MEA) emerging from the automotive industry is of great interest for aviation, but thermal management issues are still be solved. Operated below 100°C, they exhibit attractive power density but are incompatible with aircraft environment due to poor heat rejection. Also, current High Temperature FCs operated around 160°C are not at the expected level of performance for aviation, despite interesting heat rejection performances. The development of a new-generation MEA, working at temperature above 120°C and with performances equivalent to current LT-PEM MEA is the key to unlock FC applications for aviation.
NIMPHEA aims at developing - based on the development and/or optimisation of its components: catalyst layer, membrane and gas diffusion layer - a new-generation HT MEA compatible with aircraft environment and requirements, considering a system size of 1.5 MW and contributing to higher level FC targets: a power density of 1.25 W/cm² at nominal operating temperature comprised between 160°C-200°C. MEA components’ upscale synthesis and assembly process will be assessed by identifying process parameters and improved through an iterative process with lab-scale MEA tests. This disruptive MEA technology will be finally validated in a representative scale prototype (165-180 cm²) embodied in a single-cell. Simultaneously, LCA, LCC, eco-efficiency assessment and intrinsic hazard analysis will be performed to validate the MEA development. Finally, a TRL evaluation will be conducted to validate TRL4.
The Low Temperature Proton Exchange Membrane (LT-PEM) technology (incl. Membrane Electrode Assembly - MEA) emerging from the automotive industry is of great interest for aviation, but thermal management issues are still be solved. Operated below 100°C, they exhibit attractive power density but are incompatible with aircraft environment due to poor heat rejection. Also, current High Temperature FCs operated around 160°C are not at the expected level of performance for aviation, despite interesting heat rejection performances. The development of a new-generation MEA, working at temperature above 120°C and with performances equivalent to current LT-PEM MEA is the key to unlock FC applications for aviation.
NIMPHEA aims at developing - based on the development and/or optimisation of its components: catalyst layer, membrane and gas diffusion layer - a new-generation HT MEA compatible with aircraft environment and requirements, considering a system size of 1.5 MW and contributing to higher level FC targets: a power density of 1.25 W/cm² at nominal operating temperature comprised between 160°C-200°C. MEA components’ upscale synthesis and assembly process will be assessed by identifying process parameters and improved through an iterative process with lab-scale MEA tests. This disruptive MEA technology will be finally validated in a representative scale prototype (165-180 cm²) embodied in a single-cell. Simultaneously, LCA, LCC, eco-efficiency assessment and intrinsic hazard analysis will be performed to validate the MEA development. Finally, a TRL evaluation will be conducted to validate TRL4.
In the first period of the project, all very first technical design tasks for a MEA for aeronautical application (specification, MEA architecture, compliance matrix and testing harmonization) are complete and a first generation of each core-components (Carbon support; active material; ionomer; membrane) were developed and evaluated up to the single-cell level, as well as their scale-up to prepare electrodes ranging from 5 to 45 cm2.
The ionomer-H3PO4-electrocatalyst interactions were carefully investigated by electrochemical methods at T < 80°C and by spectroscopic methods. The performances/durability of the electrocatalysts were investigated in liquid electrolyte up to 65°C, with the objective of using the trends observed at low temperatures as indicators of the expected performances in HT-PEMFCs.
To perform this research, manufacturing tools have been used to produce several samples of MEA: Samples loaded with PVD method and polyol method, and two partners (CEA and Advent) performed the MEA assembly. Regarding the test bench, the ability of the test rig to perform the tests was checked and necessary adaptations were determined. They are now implemented.
Life cycle analysis has started and considered three levels of analysis: component level (MEA), stack level and propulsion system level. Models have been built and a preliminary analysis at MEA level has been performed. MEA safety analysis has shown that no catastrophic hazards have been identified.
During RP2, Safran Tech’s participation to the project was terminated due to technical reasons, as described in WP3, leading to a Grant agreement amendment. New major project risk was raised on MEA scaling up leading to specific technical meetings between the involved partners and the coordinator to assess and monitor this risk. These actions are still ongoing.
A second generation of core-components was successfully developed and a third generation currently being finalized, showing improvements in scalability, performances (e.g. specific surface, reaction rate, IEC), fabrication rate, etc. This second generation was transferred to WP#4. In parallel, innovative tools to understand electrochemical interfaces were integrated to the consortium expertise, namely (i) a gas diffusion electrode cell allowing to study the influence of the electrolyte & ionomer onto the reaction rate in idealized conditions but at high reaction rate and (ii) an electrochemical impedance spectroscopy tool to study the influence of the core-components developed within NIMPHEA on the capacitive response of the porous network.
Since the last reporting period, CEA manufactured 11 Gen2 cathodes (25 and 45 cm²) using a Pt/C catalyst from CNRS and a PWM ionomer from Advent. These were integrated into MEAs with Advent's IPM1 membrane and tested by both CEA and Advent. Initial tests in 25 and 45 cm² technical cells showed poor reproducibility and rapid performance decay. CEA then optimized the electrode composition using the same materials, leading to significantly improved and more stable performance in 1.8 cm² differential cells—outperforming both Gen1 and baseline IP MEAs. These promising results support further integration and testing at larger scales, with 45 cm² electrode manufacturing currently underway.
Advent began testing the first 45 cm² electrode received from CEA. For the MEA assembly, Advent used the IPM1 membrane combined with Advent Anode Electrode, featuring a platinum loading of 0.5 mg/cm². The lamination process followed Advent’s standard protocol. Initial testing revealed a low open-circuit voltage (OCV), along with poor and rapidly degrading performance. Subsequently, Advent continued testing using a 5 cm² MEA under high flow conditions. This setup showed a higher OCV during activation and a slight improvement in performance compared to the 45 cm² MEA. However, the results remained significantly below the performance of the baseline IPM1 MEA.
In parallel, CEA continued developing a 1D electrochemical model, using experimental I-V and EIS data from both RP1 and RP2 for Advent PBI and IP MEAs. A sensitivity analysis was performed to evaluate the impact of H₃PO₄ adsorption, O2 solubility, and diffusion on performance. These efforts aim to support the design and de-risking of Gen3 MEAs
At Fraunhofer ICT the base line testing of state-of-the-art PBI/H3PO4 MEAs was continued by performing first long-term tests as well as an adaption of the flight profile test both described in deliverable D2.4 from reporting period 1. The required amendments of the test rig described in D 5.1 are ordered so that a full scale performance measurements using D2.4 protocols will be available. Also the technical solution for measurements with hard stop compression of the MEA in balticFuelCell cell fixtures reported in the first periodic report was successfully implemented and validated during the first months of this reporting period.
Environmental life-cycle assessment has been completed, considering three levels of analysis: component level (MEA), stack level, and power train level. Moreover, life-cycle costing has started, focusing on establishing the methodological framework for the economic analysis.
MEA safety analysis, with updates of the intrinsic hazard analysis embedding generation #1 and generation #2 MEA components, has shown that no catastrophic hazards have been identified.
The ionomer-H3PO4-electrocatalyst interactions were carefully investigated by electrochemical methods at T < 80°C and by spectroscopic methods. The performances/durability of the electrocatalysts were investigated in liquid electrolyte up to 65°C, with the objective of using the trends observed at low temperatures as indicators of the expected performances in HT-PEMFCs.
To perform this research, manufacturing tools have been used to produce several samples of MEA: Samples loaded with PVD method and polyol method, and two partners (CEA and Advent) performed the MEA assembly. Regarding the test bench, the ability of the test rig to perform the tests was checked and necessary adaptations were determined. They are now implemented.
Life cycle analysis has started and considered three levels of analysis: component level (MEA), stack level and propulsion system level. Models have been built and a preliminary analysis at MEA level has been performed. MEA safety analysis has shown that no catastrophic hazards have been identified.
During RP2, Safran Tech’s participation to the project was terminated due to technical reasons, as described in WP3, leading to a Grant agreement amendment. New major project risk was raised on MEA scaling up leading to specific technical meetings between the involved partners and the coordinator to assess and monitor this risk. These actions are still ongoing.
A second generation of core-components was successfully developed and a third generation currently being finalized, showing improvements in scalability, performances (e.g. specific surface, reaction rate, IEC), fabrication rate, etc. This second generation was transferred to WP#4. In parallel, innovative tools to understand electrochemical interfaces were integrated to the consortium expertise, namely (i) a gas diffusion electrode cell allowing to study the influence of the electrolyte & ionomer onto the reaction rate in idealized conditions but at high reaction rate and (ii) an electrochemical impedance spectroscopy tool to study the influence of the core-components developed within NIMPHEA on the capacitive response of the porous network.
Since the last reporting period, CEA manufactured 11 Gen2 cathodes (25 and 45 cm²) using a Pt/C catalyst from CNRS and a PWM ionomer from Advent. These were integrated into MEAs with Advent's IPM1 membrane and tested by both CEA and Advent. Initial tests in 25 and 45 cm² technical cells showed poor reproducibility and rapid performance decay. CEA then optimized the electrode composition using the same materials, leading to significantly improved and more stable performance in 1.8 cm² differential cells—outperforming both Gen1 and baseline IP MEAs. These promising results support further integration and testing at larger scales, with 45 cm² electrode manufacturing currently underway.
Advent began testing the first 45 cm² electrode received from CEA. For the MEA assembly, Advent used the IPM1 membrane combined with Advent Anode Electrode, featuring a platinum loading of 0.5 mg/cm². The lamination process followed Advent’s standard protocol. Initial testing revealed a low open-circuit voltage (OCV), along with poor and rapidly degrading performance. Subsequently, Advent continued testing using a 5 cm² MEA under high flow conditions. This setup showed a higher OCV during activation and a slight improvement in performance compared to the 45 cm² MEA. However, the results remained significantly below the performance of the baseline IPM1 MEA.
In parallel, CEA continued developing a 1D electrochemical model, using experimental I-V and EIS data from both RP1 and RP2 for Advent PBI and IP MEAs. A sensitivity analysis was performed to evaluate the impact of H₃PO₄ adsorption, O2 solubility, and diffusion on performance. These efforts aim to support the design and de-risking of Gen3 MEAs
At Fraunhofer ICT the base line testing of state-of-the-art PBI/H3PO4 MEAs was continued by performing first long-term tests as well as an adaption of the flight profile test both described in deliverable D2.4 from reporting period 1. The required amendments of the test rig described in D 5.1 are ordered so that a full scale performance measurements using D2.4 protocols will be available. Also the technical solution for measurements with hard stop compression of the MEA in balticFuelCell cell fixtures reported in the first periodic report was successfully implemented and validated during the first months of this reporting period.
Environmental life-cycle assessment has been completed, considering three levels of analysis: component level (MEA), stack level, and power train level. Moreover, life-cycle costing has started, focusing on establishing the methodological framework for the economic analysis.
MEA safety analysis, with updates of the intrinsic hazard analysis embedding generation #1 and generation #2 MEA components, has shown that no catastrophic hazards have been identified.