Tokai Carbon has succeeded in developing a carbon bipolar plate for Proton Exchange Membrane Fuel Cells (PEMFC) that surpasses metal bipolar plates in terms of performance and cost.

We will be working aggressively towards the uptake of this carbon bipolar plate in applications such as portable consumer fuel cells, household fuel cells, automobile applications, and small-scale power source applications.

Feature

Carbon-based bipolar plates are promising from a corrosion resistance and cost standpoint, but their thicker thickness compared to metal bipolar plates has been the most significant obstacle. Tokai Carbon has succeeded in producing a much thinner carbon-based bipolar plate. In the past, the thinnest sections of carbon-based bipolar plates needed to have a thickness of 0.30 mm to maintain impermeability of hydrogen gas, but we have now developed the technology to form bipolar plates as thin as 0.13 mm. In addition, we have achieved the strength required to allow mechanical handling (flexibility; fracture strain is approximately 1.0% or higher) while still maintaining the excellent properties that carbon-based materials offer.

Metal bipolar plates, currently the dominant material, may be produced in corrugated configurations with a uniform thickness of around 0.10 mm. These thin metal bipolar plates have many advantages over carbon-based alternatives in terms of strength, gas impermeability and specific resistivity, among others.

At a reduced thickness of 0.13 mm, carbon-based bipolar plates offer great advantages in comparison to metal in terms of heat capacity and weight. In addition, Tokai's material can be molded into an almost 90-degree angle and therefore has a broader contact area, which results in lower total contact resistance, making it favorable for electricity generation when compared with metal bipolar plates.

Tokai Carbon has been able to reduce the hot-press molding term down to approximately one minute from the seven minutes that it had previously taken. This means we have achieved high productivity comparable to that of common, inexpensive plastic products that can be produced in around one minute using injection molding. Utilizing this rapid hot-press molding technology, Tokai Carbon has the production capacity to produce around 30,000 A4-sized plates per month.

We have also made advancements in terms of recycling. We are now able to reuse more than half of the graphite powder from the used bipolar plates, after removing the resin ingredient, as a raw material in the production of carbon-based bipolar plates. Tokai Carbon is also a manufacturer of graphite electrodes, making it possible for us to effectively utilize the remaining graphite power in the fabrication of graphite products. Since we purchase large amounts of graphite powder to use as raw material in the manufacture of graphite electrodes, we also enjoy advantages in the procurement of this material.