Screen printing approach for high throughput and flexible adhesive deposition in graphite bipolar plate production

The struggle against climate change necessitates innovative technologies for storing and utilizing renewable energy. Hydrogen is considered a promising solution for harnessing renewable energy in a wide range of applications. In addition to its application as a raw material in the steel and the chemical industry, hydrogen can also be utilized as an energy carrier in conjunction with fuel cells (e.g. with Polymer Electrolyte Membrane Fuel Cells PEMFC) for heavy-duty vehicles, emergency power supplies or the maritime sector. To achieve the required electrical voltages for these applications, several hundred cells are assembled to a stack. A crucial component of an individual cell alongside the Membrane Electrode Assembly (MEA) is the Bipolar Plate (BPP), consisting of two bonded Bipolar Half Plates (BPHP). The BPP enables an inflow of reactive media, the cooling of the cell and is also required for the electrical contacting of the stacked cells as well as the overall mechanical stability. According to previous studies, fully bonded BPPs, especially in the flow field, significantly improve both mechanical and electrical properties of the entire stack. The here presented innovative approach for adhesive deposition aims at bonding graphitic BPHPs to BPPs with a high throughput capability while maintaining high flexibility and process stability. The process is based on the conventional screen printing technique, which in this case is performed without a stencil, allowing for a high flexibility regarding the cell geometry. Furthermore, the range of usable adhesives can be expanded with minor adjustments, allowing for not only paste adhesives but also thermally activated powders. With the presented approach, the adhesive volume can be controlled precisely and applied uniformly by selecting a suitable screen. The feasibility of the approach was tested and initial parameter estimations for potential industrial implementation were determined.