Kompressionseigenschaften der Gasdiffusionslage einer Hochtemperatur-Polymerelektrolyt-Brennstoffzelle

The high-temperature polymer electrolyte fuel cell (HT-PEFC) has a wide range of applications in stationary applications such as combined heat and power generation or as uninterruptible power supply, as well as on-board power supply in mobile applications. The aim of the present work is to investigate the compression behavior of the gas diffusion layer(GDL) used in an HT-PEFC in combination with the membrane electrode assembly (MEA). To characterize the compression behavior, the parameters porosity, permeability and the intrusion behavior of the GDL into the flow channel are used. Using a computer tomograph, 3D modelsof the compressed GDL are generated in the MEA assembly and the relevant parameters aredetermined in post-processing. Based on the obtained properties of the compressed GDL, HT-PEFCsingle cell tests are carried out with two commercial MEAs to show the influence of thechange in properties of the GDL on cell performance.For the ex-situ tests, three different GDL types, namely H2315 C2 from Freudenberg FCCT SE& Co. KG (non-woven), TGP-H-060 from Toray Industries Inc. (paper) and AvCarb 1071HCB(woven) from AvCarb Material Solutions were used. In a first compression cell, the GDLs in theMEA assembly are compressed by a one-sided channel-rib structure with channel widths of 0,8 and 1,0 mm, and the porosity, as well as the penetration behavior and permeability are determined. The non-woven and paper GDLs show an equivalent behavior both on the changing compression and on the variation of the channel width. Regardless of the channel width, theporosity of the three GDLs decreases linearly. Against the background of manufacturing and assembly tolerances, the influence of the flowfield plate misalignment on the intrusion behavior in five channel pairs was investigated in a second compression cell with constant compression. As the misalignment increases, the point of maximum intrusion depth also shifts and the catalyst coated membrane (CCM) moves towards the channels. The single cell experiments with varying compression show that for a maximum power density, compressions of up to 15% can be selected for the MEA with non-woven GDL and up to20% for the MEA with woven GDL. A misalignment of the flowfield plates by almost 50%(1 mm) has no significant influence on the performance of an HT-PEFC single cell for bothMEAs investigated