PEMFC durability testing using heavy-duty load cycles

EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing 1 – 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244129 A1008 Page 1/5 A1008 PEMFC durability testing using heavy-duty load cycles Jens Mitzel* (1), Juan Sanchez-Monreal (1), Julien Durst (2), Kevin Godard (2), Christophe Vacquier (2) Pawel Gazdzicki (1) (1) German Aerospace Center (DLR), Institute of Engineering Thermodynamics, Stuttgart/Germany; (2) SYMBIO, A front-runner hydrogen company, Saint-Fons/France; *Contact corresponding authors: www.EFCF.com/ContactRequest Abstract PEMFC is a key technology for the decarbonization of the transport sector. The use of hydrogen powered vehicles appears as most promising solution to maintain driving range and refueling time competitive to traditional combustion engine vehicles. Both aspects are of high importance for Heavy-Duty Vehicles (HDV), but the PEMFC implementation in this type of vehicles has been addressed only recently. Thereby, the main focus of development has shifted towards operation at higher voltages to increase fuel efficiency and towards durability. The PEMTASTIC project [1] aims to meet these key technical challenges for the membrane-electrode assembly (MEA) by a combination of model-based MEA design and innovative materials tailored for heavy duty operation at elevated temperatures. In contrast to the automotive application, there is still a lack of harmonized load cycles for heavy-duty application. Therefore, this work will demonstrate how to select a representative mission profile and how to derive a PEMFC load cycle from this profile based on the selected vehicle characteristics and hybridization strategy (Figure 1). In this way, a HD representative cycle is defined for durability tests on stack level by a current density profile and for differential cells by a cell voltage profile. This approach enables the break-down of degradation analysis to differential cells. Most important parameters for reliable and reproducible durability characterization will be demonstrated. Furthermore, results of degradation tests for different MEAs using this HD load cycle will be presented together with in-situ and ex-situ characterization results to demonstrate the importance of such a HD representative load cycle and its impact on the different materials of the MEA components. The project PEMTASTIC (GA number: 10110143) is supported by the Clean Hydrogen Partnership and its members Hydrogen Europe and Hydrogen Europe Research. Figure 1: Analysis of truck power requirements based on mission profiles. EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing 1 – 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244129 A1008 Page 2/5 Introduction The reduction of greenhouse gas emissions is necessary in order to achieve the climate targets set in Europe. Looking at the global CO2 avoidance potential [2], over 3.1 Gt (around 50%) can be attributed to the transport sector, of which around 25% is attributable to heavy goods transport (Figure 2A). This share is expected to increase to 40% by 2030. Reducing emissions from heavy goods vehicles is therefore an important goal for achieving the climate targets set by the EU in the transport sector. The electrification of heavy goods transport is increasingly becoming the focus of fuel cell applications due to advantages such as long range, fast refueling and high power and energy density. Until 2020, fuel cell applications in the transport sector were mainly focused on passenger cars, light commercial vehicles and public transport. The advantages of fuel cells have already been demonstrated in these areas and the production of fuel cell components, stacks and systems is already being realized in small series. The use of fuel cell systems for heavy duty commercial vehicles is still limited to a few prototype demonstrations, but is gaining increasing attention and interest from truck OEMs. The first prototype fleets are available from Hyundai [3], Horizon Fuel Cell Technologies [4] and Toyota [5]. The first prototype trucks are also available from European companies such as Daimler Trucks [6], IVECO [7] and VDL [8]. So far, however, systems and components from the automotive industry have been used and adapted for these prototypes. This is not enough to fulfil the requirements in the heavy-duty sector. Components with a high power density, but above all with a long lifetime, must be developed. While the required power density in a truck is similar to that of a car, the required lifetime is around 6 times higher [9]. In addition, it must be emphasized that due to the requirements of the thermal management system, it is important to increase the acceptable operating temperature of the fuel cell to >95°C as part of the operating strategy in order to make fuel cells suitable for truck applications. In order to fulfil the requirements for durability and high efficiency (see Figure 2B), it is not sufficient to use materials from the automotive and stationary sectors. New component materials, cell designs and operating strategies tailored to the application must be developed for this special application. Figure 2: CO2 avoidance potential [2] by 2050 using hydrogen technologies (A) and the difference between FC for different applications in terms of cost drivers and synergies with other high-power applications. For this purpose, it is particularly important to test the performance and life time under real, application-specific conditions and load cycles. Therefore, a methodology for deriving load cycles for fuel cell test benches from real driving cycles of HDVs was developed. The application of this methodology is demonstrated using the example of a VECTO-based driving cycle. The characterization of the service life of MEAs under these real operating conditions is presented and important effects of these ageing tests on the individual MEA components are shown. EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing 1 – 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244129 A1008 Page 3/5 1. Scientific Approach Realistic HD fuel cell stack operation protocols were derived from truck mission profiles, based on standardized European duty cycles from the VECTO database. The selected HD mission profile is based on a daily drive cycle of a HD truck driver during a 11 h 45 min shift including 9 h of driving, 2 h loading goods and 45 min break (Figure 3). The mechanical power obtained from the cycle analysis is used as power demand of the electrical motor and vehicle data for a generic tractor trailer up to 40 t are used for simulation, covering vehicle mass, frontal area (air drag), and rolling resistance. Figure 3: HD mission profile selected for representative HDV operation. Semiempirical models are used to determine the operative conditions of all the components of the hybrid system and thus of the fuel cell system and its components. An application relevant hybridization strategy was applied to enable low H2 consumption to comply with high fuel efficiency requirements and avoiding most severe and damaging fuel cell and electrochemical core stressors. The fuel cell system applied for simulation is based on the M2FCT Reference Fuel Cell System for Heavy-Duty Trucks [10] and performance data of a commercial reference MEA are used for profile break-down to the stack and cell level. The PEMFC stack operating conditions are defined for stacks and technical single cells as well as for differential cells. For the latter, local operating conditions are derived are applied to differential cells allowing well controlled and accurate experiments. A key aspect is to evaluate the impact of high operation temperatures >95°C, which are present at least close to the coolant outlet. 2. Experiments/Calculations/Simulations The presented tests were carried out using a liquid-cooled PEMFC differential cell from balticFuelCells (cF12-100HA) using all parallel flow fields enabling high control of temperature and gas pressure along the entire gas channels. The active area of this cell is 12 cm² (4 cm long and 3 cm wide) and it is operated at high gas flow (hydrogen and air using stoichiometries of 10 at 3 A/cm²) to minimize oxygen depletion in the used air and to mimic gas velocities in a stack. This differential cell was operated using an in-house manufactured test station using hydrogen (grade 5.0), nitrogen (grade 5.0) and compressed ambient air (particle-filtered, dried and oil-free). The used test station is equipped with bubbler evaporators, high precision mass flow and pressure controllers, a thermostat and an electronic load. Silicon oil is used for coolant. All reactant supply pipes are electrically heated and thermally insulated to avoid water condensation in the feed streams. All tests were carried out using test protocols developed in the PEMTASTIC projects and publicly available [11]. EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing 1 – 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244129 A1008 Page 4/5 3. Results The methodology for the applied semiempirical models used to determine the operative conditions of the hybrid system components was already presented during the EFCF 2023 [12]. The resulting load cycle for differential cells is defined in cell voltage (Figure 4) to enable comparative studies between different MEAs and different local positions in the stack. These local conditions at stack air inlet and outlet are calculated based on a simple stack model using hydrogen and air in counter-flow and the coolant and air in co-flow configuration. The resulting anodic and cathodic pressure drop was calculated according to a current density of 1.5 A cm-2. The applied operating conditions are also summarized in Figure 4. Figure 4: HD mission profile selected for representative HDV operation The presented work will demonstrate the most important parameters for reliable and reproducible durability characterization. The results of several degradation tests and related in-situ and ex-situ characterization of the used MEAs will be presented. Therefore, different MEAs were analyzed and the impact of local conditions on degradation phenomena were analyzed. The presented results will identify bottlenecks in MEA design for heavy-duty application and will demonstrate how the target KPIs can be achieved through material and structural adjustments. References [1] https://pemtastic-project.eu/ [2] Energy, Environment and New Materials; de Gruyter; ISBN 9783110596243; J. Mitzel, A. K. Friedrich; Utilization of Hydrogen for Sustainable Energy and Fuels; p. 367-398; DOI: 10.1515/9783110596274. [3] https://www.hyundai.news/eu/articles/press-releases/xcient-fuel-cell-trucks-recorddriving-distance-switzerland.html [4] https://cleantechnica.com/2020/05/18/hyzon-motors-to-begin-production-of-heavyduty-fuel-cell-trucks-buses-this-year/ [5] https://pressroom.toyota.com/toyota-expands-commitment-to-hydrogen-society-withfleet-infrastructure-and-next-gen-system-debut/ [6] https://insideevs.com/news/444480/mercedes-genh2-truck-fuel-cell-concept-truck/ [7] https://www.electricmotorengineering.com/everything-ready-to-produce-the-electrictruck-by-iveco-nikola/ [8] https://newsroom.toyota.eu/vdl-groep-reveals-fuel-cell-truck-for-toyotas-europeanlogistics/ EFCF 2025: Low-Temp. Fuel Cells, Electrolysers & H2 Processing 1 – 4 July 2025, Lucerne Switzerland https://doi.org/10.5281/zenodo.17244129 A1008 Page 5/5 [9] https://www.clean-hydrogen.europa.eu/knowledge-management/strategy-map-andkey-performance-indicators/clean-hydrogen-ju-sria-key-performance-indicatorskpis_en [10] https://millionmilefuelcelltruck.org/ [11] https://pemtastic-project.eu/wp-content/uploads/2023/09/PEMTASTIC_D1.3_Publicreport-on-definition-of-FC-test-protocols_pg_draft.pdf [12] J. Sanchez-Monreal, J. Mitzel, P. Gazdzicki; EFCF 2023, A1511, Analysis of HeavyDuty Requirements and Mission Profiles to Develop ASTs for PEMFC. Keywords: EFCF2025, H2, Low Temperature Fuel Cells, Heavy-Duty, Mission Profile, Hybridization Strategy, Life Time Remark: This work is licensed under Creative Commons Attribution 4.0 International