Advanced graphite composite bipolar plates for fuel cells

Huntsman’s partners used these new resin systems to develop a new generation of fuel cells for a wide variety of needs and applications. They won a JEC Award in the Raw Material category for this achievement in 2009.

Context and new solution

The two resin systems developed by Huntsman Advanced Materials meet the stringent requirements for graphite composite fuel cells.

Philippe Christou, Technology Director EMEIA Huntsman Advanced Materials said: “Every major automotive, stationary power and back-up power manufacturer in the world is considering how best to utilize fuel cell technology to reduce carbon dioxide emissions and reliance on fossil fuels, making fuel cell components a potential boom market. Working with our partners, this is a technology breakthrough that represents major long-term opportunities.”

Since the conversion of fuel to energy takes place via an electrochemical process, the process is much cleaner, quieter and up to three times more efficient than burning fuel.

The fuel cell’s bipolar plates are said to have superior corrosion resistance, lower contact resistance, higher thermal conductivity and a longer operating life at higher temperatures. For the automotive sector, Huntsman Advanced Materials has developed a benzoxazine resin suitable for hightemperature PEM fuel cells. The resin, which operates at a continuous temperature of 120°C, has a phenolic-like backbone which gives it very good flame retardant properties together with excellent glass transition temperatures and mechanical properties. In particular, it has a very high modulus, low water absorption, near zero shrinkage and good electrical properties. For stationary power and back-up power applications, a bismaleimide resin has been developed for fuel cells operating at temperatures of up to 180°C in concentrated phosphoric acid. The resin is flame resistant and provides the fuel cells with excellent thermal and electrical conductivity, a low ionic content and can be applied in continuous high-volume manufacturing processes using conventional prepregging techniques.

Advantages versus metal

Standard metal bipolar plates can be replaced with bipolar plates made from graphite composite materials in fuel cell applications. The graphite composite bipolar plate using the new resins has the following advantages compared with the metal bipolar plate:

• superior corrosion resistance thanks to its strong chemical resistance which prevents degradation in the presence of electrolytes such as glycols or concentrated phosphoric acid;
• lighter weight for greater efficiency levels;
• long operating life (no polymer electrolyte membrane/proton exchange membrane poisoning because of low ionic levels in the resin systems);
• high-temperature resistant resin systems for automotive and stationary power applications, because fuel cells operate at higher temperatures to improve efficiency;
• low leachable ionic levels in the resin systems to avoid fuel cell damage;
• consistent electrical performance (no insulating surface is formed).

The cells have already undergone extensive testing and are expected to be commercially available soon.