Bipolar plates are core elements of fuel cell and electrolyzer stacks. Contaminations affect the efficiency and lifespan of the plates, making cleaning essential. The parts2clean presents efficient processes and systems for sustainable, automated cleaning of the plates.
(Image: acp systems)
Whether as a central pillar for emissions-free mobility or the energy transition, hydrogen technologies play a key role. As the core of a fuel cell or an electrolyzer, stacked bipolar plates (stacks) are central elements. The plates consist of an anode and a cathode with a proton-conductive membrane in between. They are made from various materials such as coated metal, graphite, and graphite-polymer compounds. Metallic bipolar plates are considered advantageous in terms of low weight and volume as well as good cold-start capability. This variant also offers the potential for relatively cost-efficient mass production, which can be further improved through economies of scale.
Bipolar plates handle gas, heat, and power management
In stacks, bipolar plates physically and electrically connect the anode of one cell with the cathode of the adjacent cell. Through integrated flow profiles (flowfields), the plates not only regulate the supply of the reaction gases hydrogen on the anode side and oxygen on the cathode side but are also responsible for temperature control of the stacks, the release of water vapor, as well as thermal and electrical energy. How efficiently they perform these multifunctional tasks determines the overall performance of a hydrogen system.
Gallery
Cleanliness – crucial for quality and efficiency
The manufacturing of bipolar plates can be summarized with the following steps: unwinding the extremely thin and very sensitive raw material from a coil, forming it into anode and cathode plates, cutting and separating, as well as coating and joining the plates. Apart from the fact that the raw material may already contain contaminants such as rolling and drawing oils or unknown foreign substances from its production, particulate and film-like impurities such as burrs, chips, fibers, dust, oils, emulsions, soot, and oxides are generated at each manufacturing step. Any of these residues can later compromise the quality of the bipolar plates, reduce efficiency and lifespan, or cause defects. The cleanliness requirements are therefore very high. To ensure this high level of component cleanliness, a cleaning process is indispensable before the joining and coating steps. A key challenge is the often invisible, chemically film-like residues on the surfaces, the composition of which is frequently unknown. Additionally, bipolar plates are manufactured at high speed, making the required cleaning time another critical factor to consider.
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Various methods are offered for cleaning. These include wet chemical cleaning with solvents and water-based media, laser cleaning, steam cleaning, CO2 snow blasting, plasma cleaning, and hydro-cleaning. These methods are used individually or in combination, tailored to the material, the contaminants to be removed, and the cleaning requirements.
Wet-chemical cleaning has become established in many processes. Solvents are effective at removing oils, greases, and particles. With water-based media, however, the often required subsequent drying results in high energy consumption and long cycle times.
Good results are achieved in very short times for the removal of filmic-chemical and particulate contaminants, soot, and oxides with steam blasting. This is based on the interaction of steam with a precisely adjusted liquid content, a high-speed airflow, and a tailored nozzle concept. Hydro-cleaning has also proven to be effective, where the cleaning medium is applied to the surface through nozzles at defined pressures and temperatures.
The dry CO2 snow blasting with liquid carbon dioxide enables both selective and full-surface removal of soot and oxides, as well as chemically film-like contaminants and particles, within very short cycle times. A promising approach is also the high-pressure (HP) CO2 blasting, where liquid carbon dioxide is used as the blasting medium at pressures of up to 4000 bar.
In addition to various cleaning systems such as chamber and immersion systems, Ecoclean offers the new EcoCvolta, a continuously operating system for cleaning bipolar plates. Tailored to specific requirements, this solution integrates various process options such as spraying, steam cleaning, hydro-cleaning, plasma cleaning, CO2 snow blasting, and drying. The specialized design of the transport system ensures that the sensitive bipolar plates are handled gently.
Through thermal and photochemical effects, the laser quickly and reliably removes contaminants such as oxides, soot, particles, and organic impurities. For fully automated surface structuring prior to coating and subsequent laser cleaning of bipolar plates, SLCR Lasertechnik has developed an innovative solution. By intentionally roughening the surface with the laser in the first step, adhesion properties can be significantly improved. The generated micro- and nanostructures increase the specific surface area, leading to better mechanical anchoring of the coating. The structuring can be adjusted depending on the material and application to achieve the best possible wetting with the coating. In the automated solution, the double-sided processing presents a particular challenge, which is addressed through the use of a specially developed robotic gripper. Laser cleaning is carried out immediately as a subsequent second step, which reduces throughput times.
Date: 08.12.2025
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Specific information on processes
The exhibitors at parts2clean provide information about these processes and systems, as well as their advantages and limitations. The international leading trade fair for industrial parts and surface cleaning will be held from October 7 to 9, 2025, parallel to Hy-Fcell (October 7 to 8) at the Stuttgart exhibition grounds (Germany). Visiting both fairs as well as the p2c.Expertforum is possible with one ticket.