The hydrogen and
fuel cell center
ZBT GmbH

From research into small series: seals for fuel cells

While increasing the number of stacks in a ramp up the technical tasks for production technologies and quality assurance for the individual components of the fuel cell becomes significantly more evident. ZBT toady makes a significant contribution to the start production of fuel cell stacks by the development and manufacturing of high-precision seals. In the meantime, seals have been produced in the five-digit number range for different customers and designs at ZBT.

The new technical center for gaskets at ZBT

processing gaskets for metal bipolar plates for automotive fuel cells

Modern fuel cell stacks and their components are becoming more and more filigree. The material thicknesses of metallic bipolar plates, for example, has been reduced from 100 μm down to 75 μm in recent years. From a design point of view the components have also become increasingly complex for increasing the power density.
This development represents a major challenge for the tightness of the fuel cell stack. The use of the volatile energy carrier hydrogen in the fuel cell requires a highly accurate reproducible seal design for each individual cell in a fuel cell stack which, for example, can be several hundred units long in automotive applications. Leaks in a single cell can ultimately lead to a complete failure of the entire fuel cell drive.
In addition to the primary task of the tightness of the individual cells, the seal in the fuel cell also has the additional task of ensuring a secure uniform force distribution in the area of ​​the active area of a bipolar plate or GDL respectively. If a seal is too high, the electronically conducting cell components diffusion layer and bipolar plate do not sufficiently contact, if it is too low, the diffusion layer becomes too much compressed so that the media can no longer be transported to the reaction zones.

By means of automated dispenser technology, stable and cost-effective solutions for the repeatable component seal are today being developed at ZBT for a wide range of fuel cell stacks. Highly complex sealing tasks e.g. in the media supply area have also been successfully developed and ultimately produced on the small scale. The toolless dispenser technology has the advantage that it is possible to react flexibly to changes in design as they occur in the development of fuel cells and pre-production. But also for large quantities, the dispenser technology seems to have a high potential: analyzes by  ZBT show that due to the relatively low plant costs, the good automation capability of the processes and ultimately the high reproducibility of the products in bulk production, dispenser technology can be compared to other processes such as screen printing and injection molding.
In order to meet the requirements regarding cleanliness, production organization and occupational health and safety, a completely new area for sealing technology was set up at ZBT in 2016. In this separate workspace, which has been set up as a gray area, two independent automatic dispensers are avable, with which both research and development and production tasks can be targeted and handled in compliance with the nexessary high quality standards. In addition,  mixing stations, ovens and other handling facilities are on site.
It is attractive for the customers that the production know-how can be transferred at the start of serial production, but the flexible structures of the research and development service provider ZBT can be used up to then.

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