Fluorine-free materials for the fuel cell or electrolysis membrane are an important basis for the recycling capability of future systems. The first sub-goal of the project is a complete loss-break-down (LBD) analysis of a fluorine-free membrane fuel cell. In this analysis, all occurring, electrochemical loss mechanisms are considered and compared in a quantification. By comparison with a LBD analysis of a conventional Nafion-ionomer-based fuel cell thus advantages and weaknesses or potential for improvement can be explored. The LBD analysis thus provides a comprehensive picture of fluorine-free fuel cell characteristics. The results of this sub-goal are incorporated into the process development of the project partner MPI. The second sub-goal of the subproject relates to the reconstruction of the microstructure. Thus, within the subproject, the microstructure of a fluorine-free cathode catalyst layer is to be investigated for the first time by reconstruction. This has already been established at Hahn-Schickard for conventional catalyst layers for fuel cells and electrolysis cells. For cathodes with fluorine-free ionomers, however, there is no information about the microstructure. The information thus extracted is essential for the process development of the electrode production.