The markets: Fuel cells and batteries (2014)

Reinforced thermosets and thermoplastics are increasingly the keys to the expansion of both fuel-cell and battery technologies aimed at the transportation industry.

According to Fuel Cell Capacity and Cost Trends, published in July 2013 by Wiley-VCH Verlag GmbH & Co. KGaA (Weinheim, Germany, http://www.chemistryviews.org), sales of fuel cells and hydrogen systems generated over $1 billion in 2012 and are forecast to increase to over $2 billion in 2013. Growth was due in part, to the fact that production costs of low-temperature fuel cells for transportation purposes are falling, but market penetration for fuel cell vehicles and portable fuel cells is predicted to remain low in the near future. Fuel cell systems of all types are making their strongest inroads (by afr) outside the EU and North America. Asia accounted in 2012, for almost one-half of the fuel cell market, North America one-third more, leaving Europe with a not-quite one-sixth share, leaving the remaining 2 percent or so to the Rest of the World.

Composites make up the fuel-cell system’s bipolar plates, end plates, fuel tanks and other system components. In the past, thermoset materials were thought to be limited to lower volume and stationary applications, due to their longer mold cycle times, higher scrap rates and an inability to produce molded composite plates as thin as stamped metal plates. More recently, however, these issues have been overcome, providing a clear advantage over metals in high-temperature and low-temperature PEM fuel cells where power density is a secondary requirement (i.e., stationary applications). Chopped carbon fiber and graphite particle filled/vinyl ester bulk molding compounds (BMCs) are finding wide use in bi-polar plates for low-temperature PEM fuel cells. BMC cost has declined significantly as volumes have increased.  Similarly, molding cycles once measured in minutes are now routinely completed in seconds, due to formulation improvements and the capability to make thinner plate cross sections.

Vinyl ester-based bulk molding compounds with carbon filler and fiber reinforcements are available from several suppliers, including BMCI (West Chicago, Ill.), Premix Inc. (North Kingsville, Ohio) and Bac2 (Southampton, U.K.).

Although automakers expressed interest in taking fuel-cell powered cars beyond the concept stage in the 2011-2012 timeframe, 2013 saw a strong surge in electric vehicle development by OEMs anxious to meet looming CAFÉ and CO2 emission standards, This, in turn, has spurred both research into and production of battery packs lightweighted with composites. Commercially available hybrid and plug-in electric cars have lacked the driving range of their gas- and diesel-powered counterparts due, in part, to battery weight. General Motors’ (GM, Detroit, Mich.) Chevy Volt exemplifies a new generation of lighter lithium-ion batteries.

The Volt’s rechargeable energy storage system is housed in a glass fiber-reinforced thermoplastic battery pack with an integrated, fluid-cooled thermal management system. Inside, 135 repeating frames, each approximately 250 mm wide and tall by 15 mm thick (9.8 inches square by 0.60 inch thick), and 18 similarly sized end frames encase 288 battery cells. (Read more about the development of the Chevy Volt’s composite battery pack in “Chevy Volt battery pack: Rugged but precise,” under “Editor’s Picks” at top right. Also see the photos at left.)  GM’s partners in the project include material supplier BASF AG (Ludwigshafen, Germany), molder MANN+HUMMEL (Portage, Mich.) and Canadian toolmaker Omega Corp. (Old Castle, Ontario).

Related Content

Chevy Volt battery pack: Rugged but precise

GM and partners engineer composites for this complex assembly with an accent on repeatability.