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Measurement specification and measuring device for electrical conductance developed - BePPel project successfully completed

The development of a standardised method for measuring physical parameters was the aim of the joint project "BePPel" (bipolar plates for fuel cells and electrolysers) - ZBT has developed a new measuring device for electrical resistances of bipolar plates.

Pressure-dependent resistance measurement

Detail of measurement equipment

Thermal conductivity measurement at ZBT: Laserflash, HotDisk and C-Therm

Simulation of the distribution of in-plane thermal conductivity within an injection-moulded bipolar plate

Verbundvorhaben NIP II – BePPel – Bipolarplatten für Brennstoffzellen und Elektrolyseure 03B11002B / 03B11002B2 01.04.2017 – 31.03.2020

In a consortium of six major German research institutions funded by the Federal Ministry of Transport and Digital Infrastructure and the National Organisation Hydrogen and Fuel Cell Technology (NOW), the measurement standards required by industry were developed and implemented in the sense of improved quality monitoring of bipolar plates for fuel cells and electrolysers (BePPel).

The focus of the work at the ZBT was the development, setup and commissioning of the new measurement system, as well as the creation of a measurement specification for the uniform determination of the electrical through-plane resistances of bipolar plates. For this purpose, construction drawings and electrical circuit diagrams were prepared, a comprehensive operating manual was written, and a risk assessment was carried out so that CE certification of the device could be obtained. Thanks to the control via LabView, the test stand allows automated measurement routines with different contact pressures and different current intensities to be carried out within a very short time. At maximum contact area from BPP to measuring pole or GDL contact pressures of up to 40 bar and current densities of up to 2.5 A/cm² can be applied. As a follow-up to the project, ZBT now offers measurements on the test stand as a reference for manufacturers of bipolar plates. The newly constructed resistance measuring station will also be used at ZBT in current and future R&D projects for the characterisation of bipolar plates and GDL materials.

In addition to the work on electrical conductivity, ZBT has also carried out extensive investigations to determine the thermal conductivity of bipolar plates. For this purpose, three commercial measuring instruments were compared for the application for characterising bipolar plates. Large differences in the measurement results of the three devices were found, which could be attributed to the orientation of the filler particles within graphitic bipolar plates, among other influencing factors. For example, in the case of injection moulded BPP, the orientation of the fillers in the area close to the edges in the injection moulding direction and in the core of the sample transverse to the flow direction could be detected by means of SEM images, which has a significant influence on the thermal conductivity. Based on the investigations carried out, the flash method is preferred for the determination of the through-plane thermal conductivity of bipolar plates and a measurement specification for the determination of the through-plane thermal conductivity of BPP was designed. Furthermore, a calculation tool based on the software COMSOL Multiphysics® was developed at ZBT, which can display the distribution of thermal or electrical conductivity within a bipolar plate. Using the developed calculation tool, it is possible to extrapolate to the overall geometry of a bipolar plate on the basis of the measurement data of individual measurement points and thus also to examine structured samples metrologically.

The results of the project will be incorporated into the development of fuel cell technology and thus contribute to the climate protection policy of the Federal Republic of Germany to reduce greenhouse gas emissions. The measurement system developed and the measurement specification for determining electrical resistances (in- and through-plane) and contact resistances on both metallic and graphite bipolar plates for fuel cell systems and electrolyzers make an important contribution to the establishment of an internationally competitive supplier industry in Germany and help strengthen hydrogen and fuel cell technology in the transport sector and the energy market.

Project partner

  • DLR-Institut für Vernetzte Energiesysteme e. V.;
  • Fraunhofer Institut für Solare Energiesysteme ISE;
  • Fraunhofer-Institut für Chemische Technologie ICT;
  • Institut für Energie- und Klimaforschung (IEK), Forschungszentrum Jülich;
  • Zentrum für BrennstoffzellenTechnik GmbH;
  • Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg.

Further documents and information

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