Evaluation of the crack structure of HT PEFC electrodes from in situ synchrotron radiographs

One of the main goals for improvement of high temperature polymer electrolyte fuel cells HT PEFCs is the increase of the fuel cell performance under different operating conditions. We investigated the correlation between operating conditions and structural changes in the electrodes by means of in situ through plane synchrotron X ray radiography. From the radiographs it is possible to clearly distinguish between the electrode crack structure beneath the ribs and beneath the channels of the flow field. We present a statistical method to analyze these crack structures. For this purpose a radar method was developed in order to obtain the width of the cracks at many different locations and the distribution of crack widths. We found a different behavior of cracks located beneath the ribs and beneath the channels and an influence of the operating conditions on local regions of the crack structur