High-Precision Thin Wall Bipolar Plates for Fuel Cell Applications via Injection Compression Molding with Dynamic...

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Processing

Background:

• Growing demand for polymer compound bipolar plates in PEMFCs due to cost and lifetime benefits over metallic alternatives.
• Key challenge: achieving sufficient electrical conductivity requires high filler content, increasing viscosity and limiting conventional injection molding.
• High filler content hinders processing of thin-walled bipolar plates with good dimensional stability due to limitations in aspect ratio.

Purpose of the Study:

• To evaluate the processability of highly modified, electrically conductive polymer systems into thin-walled, dimensionally stable bipolar plates.
• To develop and assess an injection compression molding process with dynamic mold temperature control (ICM-DT) for these materials.

Main Methods:

• Developed an injection compression molding process with dynamic mold temperature control (ICM-DT).
• Prepared a compound of polypropylene (PP) and graphite flakes, characterizing its filler content, electrical conductivity, and solidification range.
• Conducted ICM-DT experiments varying mold temperature, compression force, and employing multi-stage compression/decompression steps.

Main Results:

• Achieved up to a 125% increase in plate aspect ratio with maximum filler content compared to conventional injection molding.
• Optimized thickness dimensional stability using the multi-stage ICM-DT process, with a maximum deviation of 3% over the flow path.
• Demonstrated successful processing of highly filled conductive polymer compounds into thin-walled bipolar plates.

Conclusions:

• The ICM-DT process is effective for manufacturing advanced bipolar plates for PEMFCs using conductive polymer compounds.
• This method overcomes limitations of conventional injection molding, enabling improved aspect ratios and dimensional stability.
• The developed process facilitates the production of cost-effective and high-performance bipolar plates for fuel cell applications.