This dataset corresponds to the publication XXX. Detailed experimental and data treatment description is found thereof. The different BPM variants are grouped in “series” with capital letters corresponding to the materials described in the paper: A,B: commercial BPM with GDL at anode C,Z: commercial BPM with Ti-PTL at anode D: custom BPM E: microporous BPM F: mesoporous BPM G: microporous BPM The file “sample_operation_conditons.txt” gives an overview of the operation condition and structural degradation of each sample. Due to the large number of files, the different processing stages are bundled in the following zip files: 00_processing_code: a snapshot of the git repository containing the processing and analysis code (also at github.com:Pescatore23/coely_postmortem.git) 01: Each sample (e.g. E_3, i.e. E-series, sample 3) is contained within its own zip file holding the X-ray projections, initial volume reconstruction, aligned and cropped volume, and registered volume for each scan: preop – before operation/BOL, postop_1 – during operation/1st scan, postop_2 - after operation/EOL 02_Electrochemistry_data: the BioLogic files containing the electrochemical performance corresponding to the recorded XTM. The series and numeral identifiers match with the corresponding XTM images. Analysis was performed by comparing timestamps of image and electrochemistry data to attribute passed charges to observed changes in the images. 03_microscopy_images: microscopic inspection of custom BPM (light microscope and SEM) 04_processing: intermediate processing steps, e.g. segmentation 05_analysis: extracted quantitative data