Innovative technology for the quality testing of fuel cells

© Campus Schwarzwald

Hydrogen produced with regenerative energy is an important energy carrier for the mobility of the future. The demand for fuel cell stacks, which convert hydrogen into electrical energy, will therefore increase rapidly in the coming years. Researchers at Fraunhofer IPA and the Schwarzwald Campus are now developing an innovative quality testing process together with several industry partners that saves time and money in manufacturing.

»Automation in the production of fuel cells is still in its infancy. So far, manufacturing has been more of a craft,« reports Dr. Friedrich-Wilhelm Speckmann, Group Leader Hydrogen Technology at Fraunhofer IPA. »If the energy transition is to succeed and especially if green hydrogen is to be used as an energy carrier in heavy-duty transport, then we need efficient production lines as soon as possible, as well as quick and cost-effective quality tests for fuel cell stacks.«

However, quality control is currently the bottleneck in production. Robots can quickly and precisely stack fuel cells, but then each of these stacks, called a stack, must be connected to various measuring devices and checked. In the FastPeM project – the abbreviation stands for »Accelerated Testing Procedure for Mass Production of Fuel Cell Stacks« – Speckmann, together with researchers from the Schwarzwald Campus and industry partners, now aims to develop a test bench demonstrator that allows the electrochemical properties of a stack to be quickly and efficiently determined using innovative technologies.

»The Schwarzwald Campus is the ideal location for this project, as a fully automated stacking system is currently being set up here,« emphasizes the researcher. And Stefan Bogenrieder, Managing Director of Schwarzwald Campus, adds: »The Research Center for Intelligent Hydrogen Circular Economy in North Black Forest will provide regional and supra-regional companies and municipalities with advantages and expertise in mass-compatible fuel cell manufacturing.« He is pleased that the subproject FastPEM has now also started.

Accelerated End-of-Line Testing

In the pilot plant, a robotic arm stacks the layers on top of each other: each fuel cell consists of two thin electrodes with a membrane in between, as well as a bipolar plate through which hydrogen and air oxygen are later supplied. Within 15 minutes, a package of about 400 cells is created, which can then be pressed and tensioned. »Since every manufacturing step in this demonstrator is digitally documented, we have a comprehensive data treasure trove that we can use for quality assurance,« says Speckmann.

Testing a finished stack is currently relatively time-consuming: first, it must be tested whether the stack is airtight or whether gas, which is fed under pressure into the cells, escapes. Then, the performance curve must be determined, showing at which voltages which current densities occur. »In the FastPeM project, we now want to research how these processes can be optimized by, for example, combining both steps,« explains the engineer.

Saving Time with Digital Twins

A key role will be played by virtual techniques: the production facility and testing setup will be equipped with measurement technology that feeds sensor data into a simulation model in real time. The digital twin thus created not only models the processes but also each component in detail. Based on this extensive data set, the electrochemical properties of individual cells and complete stacks can be predicted. »The virtually calculated performance characteristic curves only need to be verified by spot measurements. Long measurement series can thus be avoided; it is probably sufficient to perform individual measurements. If these match the predictions, no further tests are necessary,« explains Speckmann. The time required can be significantly reduced if the process is successfully implemented.

For companies manufacturing fuel cells, this time saving would be a real gain. However, it will still take some time before results are available: the FastPeM project, which started on June 1, will run until 2027. Then, the test stand for mass production of fuel cell stacks is also expected to be completed.

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H2BlackForest funded with approximately 7.2 million euros in total

To expand regional innovation capacity and promote sustainable urban and regional development, the European Union’s regional policy provides a total of 80 million euros from the European Regional Development Fund (ERDF) in the competition »RegioWIN 2030«. The Research Center for Intelligent Hydrogen Circular Economy »H2BlackForest« of Fraunhofer IPA, the IFF of the University of Stuttgart, and the Schwarzwald Campus has been recognized as a lighthouse project of the North Black Forest region. A total of 4.8 million euros has been approved for the project for the funding period 2021–2027. An additional 2.4 million euros are supplemented by state funds. Together with the contributions of the participating partners, the total research scope amounts to 12 million euros. The administrative authority of the competition is the Ministry of Food, Rural Areas, and Consumer Protection (MLR).