During operation, it is important to reliably separate the media used, for example oxygen and hydrogen in the case of the PEM fuel cell. Reduced performance up to a complete failure of the stack would be possible consequences of a leak.
But it is not only operational reliability that is important at the smallest level, the individual cell. To be competitive, it also requires fast and reliable production processes.
CMC Klebetechnik offers solutions for both areas - operational reliability and high production speed:
If you have any questions, please contact:
Tel.: +49 6233 872 356
E-Mail: friederici (at) cmc.de
Sealing and stabilisation of the MEA
So-called subgasket seals are used to mechanically stabilise the MEA outside the active area. CMC 61145 is a laminate adhesive tape specified for this application. It consists of a thin Kaladex® or Teonex® PEN film coated with a hydrolysis-stable PSA special adhesive. The pressure-sensitive adhesive does not cause "poisoning" of the catalyst coating or increase the conductivity of the cooling medium. The advantage of the permanently elastic adhesive is its long-term function as a seal (subgasket) between the membrane (e.g. Nafion®) and the frame formed by the film. The frame stabilises the thin membrane film and makes installation much easier. Compared to other sealing concepts, the main advantage of CMC 61145 is the extremely low thickness (length of the stack), the high pressure resistance and the simple process control during production.
The standard film has a thickness of 25µm, but 50µm and 100µm film thicknesses are also possible on request. Other polymers for higher hydrolysis stability are also possible, e.g. PPS, PFA, PPSU, PEEK.
Since CMC Klebetechnik itself is the manufacturer of the product, the required layer thickness of the adhesive can also be adapted to the thickness of the electrodes (GDL, MPL, CCM).
Manufacturing aid for the roll-to-roll method
In order to be able to manufacture as quickly as possible and thus cost-effectively, the production of MEA units in a roll-to-roll process is the obvious choice. This continuous production process has been in use for a long time, e.g. in label production. The packaging industry is also very familiar with the reel-to-reel process, because it is often important to be able to produce large quantities of packaging quickly and cost-effectively.
The initially stable PEN film from CMC 61145 becomes very unstable when the media passages and the central opening for the membrane are punched out. It is almost impossible to guide the subgasket tape through a lamination process in this unstable state.
This can be remedied by a special adhesive tape from CMC-Klebetechnik: CMC 12089. This relatively thick polyester adhesive tape (also available in 50µm) can be laminated with the PEN film before the die-cutting process. Since the CMC 12089 adhesive tape is not punched through during the subsequent die-cutting process (kiss-cut), it remains as a stable carrier for the further roll-to-roll process. This enables precise lamination between the two CMC 61145 subgasket films and the inner membrane. The relatively thick polyester stabilisation film is not stretched by the tensile forces even in a hot lamination process.
After the lamination step, the CMC 12089 adhesive tape can be removed from the composite without leaving any residue and with minimal effort thanks to the special adhesive.
With the CMC 12089 auxiliary laminating film, it is possible for automation specialists to switch from the comparatively slow process of "stacking" individual parts to the considerably faster process of roll-to-roll laminating. This is because it is now possible to master the high accuracy requirements and control the web tension at high speeds.
Extended possibilities on request
In the overall composite of a single fuel cell with the bipolar plates on both sides, it can be advantageous to use a subgas basket frame that is coated on both sides. In this way, the functional membrane is sealed on one side. The coating on the other side (e.g. silicone) then serves as a seal towards the bipolar plate (or GDL depending on the design).
The subgasket film CMC 61145 and the laminating aid film CMC 12089 are key products for the modern, fast and cost-effective mass production of PEM fuel cells, PEM electrolyzers and the redox flow batteries that will become even more popular in the future.
Adhesive tapes for MEA production