The project aims to enable the knowledge-based design of cathode air filters for applications in China and is supplemented by a parallel application for funding from the Chinese MoST (Ministry of Science and Technology) for bilateral research projects in the field of fuel cells. Partners on the Chinese side are Tongji University, Shanghai, MANN+HUMMEL China, and Weichai as an OEM partner for trials.
The service life of a PEM fuel cell system depends largely on the cleanliness of the cathode air. The harmful influence of gases such as NH3, NOx und SO2 has already been investigated, as has the effective protection provided by filters with activated carbons that can selectively adsorb these harmful gases. As the mass-related storage capacity of activated carbons for harmful gases is limited, it is essential for the filter design to know the amount of harmful gas acting on the filter in real operation. Field tests in Germany have shown that this is highly dependent on the local air quality. Furthermore, air quality data is determined which serves as a basis for the knowledge-based design of cathode air filters for applications in China.
The aim of the research project is to develop a new type of cathode air filter system with integrated breakthrough sensors with electrochemically active surfaces for the gases NH3, NOx und SO2 for testing in China. Furthermore, the development and testing of a simulation tool for the design of cathode air filters with regard to harmful gas adsorption, including validation. The sensor array intended for this purpose is being developed on the basis of gas-sensitive layers with control of cross-sensitivities and detection limits in the trace concentration range. For this purpose, an intelligent signal evaluation with compensation of temperature and humidity influences for use in the commercial vehicle sector is being produced in China. This leads to the derivation of a knowledge-based design theory for cathode air filters on the basis of laboratory and field tests.
The central task of the fem is the development of sensor layers, i.e. electrochemically active surfaces that react sensitively and selectively to selected harmful gases or mixtures in the sub-ppm range. Signal generation is to be detected according to the principle of gas-solid interaction. Intrinsically conductive polymers such as polyaniline or polypyrrole should first be electrochemically applied to suitable 3D carrier materials - e.g. interdigital electrodes, printed electronics - as these are particularly suitable for generating a breakthrough sensor signal due to their fast response times. Furthermore, a certain selectivity must be matched to the respective pollutant gas (NH3, NOx und SO2), which is why the polymer layers must be functionalised. This task is to be performed by metals (e.g. Ag, Cu), metal alloys (AgCu, CuZn) and metal oxides (ZnO, SnO2) are taken over. These are then incorporated into the polymer layer in the form of nanoparticles, either electrochemically using pulse plating technology or as co-deposition, which gives the sensors their selectivity for the respective pollutant gas. The novel layers are documented using the characterisation options available at the institute. The samples produced will be made available to the project partner IUTA in order to test the gas-sensitive coatings for sensor arrays for different concentration ranges of gases/gas mixtures. The coating systems must be produced for certain harmful gases in such a way that cross-sensitivities (humidity, temperature, etc.) on the sensor array and cross-reactions are avoided. The different gas sensors are finally assembled into a sensor array and tested under real conditions for use in the filter system at Mann+Hummel. This is followed by further characterisation of the coating of returns from the field on the fem.
The project FKZ 03B11025A (ISAAC) is funded by the Federal Ministry for Digital and Transport Affairs as part of the National Innovation Programme for Hydrogen and Fuel Cell Technology. The funding guideline is coordinated by NOW GmbH and implemented by Project Management Jülich (PtJ).