<b>In-Situ Characterization of Cathode Catalyst Degradation in PEM Fuel Cells</b>

The composition and morphology of the cathode catalyst layer (CCL) have a significant impact on the performance and stability of polymer electrolyte membrane fuel cells (PEMFC). Understanding the primary degradation mechanism of the CCL and its influencing factors is crucial for optimizing PEMFC performance and durability. Within this work, we present comprehensive in-situ characterization data focused on cathode catalyst degradation. The dataset consists of 36 unique durability tests with over 4000 testing hours, including variations in the cathode ionomer to carbon ratio, platinum on carbon ratio, ionomer equivalent weight, and carbon support type. The applied accelerated stress tests were conducted with different upper potential limits and relative humidities. Characterization techniques including IV-curves, limiting current measurements, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to analyse changes in performance, charge and mass transfer, and electrochemically active surface area of the catalyst. The aim of the dataset is to improve the understanding of catalyst degradation by allowing comparisons across material variations and provide practical information for other researchers in the field.The uploaded folders contain the following:<b>01-Data:</b> This folder contains the data of all degradation tests. The data is structured in form of a sub-folder system, with the main sub-folder level representing the test runs (cell 1 – 42, as in manuscript Table 1), inheriting sub-folders for the test method (step 1 – 12, as in manuscript Table 2) and finally subfolders for the degradation interval (0 – 30k AST cycles). At the end of each sub folder path the corresponding data is stored in form of a csv-file, where some files contain multiple rows and columns (e.g. raw CV or impedance data), while others consist of a single evaluated parameter value (e.g. ECSA and protonic resistance).<br><b>02-Testing_overview:</b> This folder contains an Excel-File with Table 1 and 2 from the manuscript. The tables provide an overview of all conducted tests and the respective material and AST variation, as well as an overview of the applied testing protocol.<b>03-Evaluation_scripts:</b> This folder contains exemplary evaluation code for the applied characterization methods. The script are meant to show an exemplary way of evaluating the parameter values (e.g. ECSA) from the respective raw data (e.g. CV) found in the storage.For further context and description of the data, please refer to the referenced manuscript.