The markets: Fuel cells and batteries (2015)
Composites can make up the bipolar plates, end plates, fuel tanks and other system components of fuel-cell electric power systems as well as lightweight cases and components for battery electric vehicles. there will be much activity on both fronts.
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Composites can make up the bipolar plates, end plates, fuel tanks and other system components of fuel-cell electric power systems. 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. Chopped carbon fiber and graphite particle filled/vinyl ester Bulk Molding Compounds Inc. (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.
According to Fuel Cell Capacity and Cost Trends, published in July 2013 by Wiley-VCH Verlag GmbH & Co. KGaA (Weinheim, Germany), sales of fuel cells and hydrogen containment systems generated more than US$1 billion in 2012 and were forecast to increase to more than US$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. That said, most major automakers have made significant progress in the development of fuel-cell powered electric vehicles, but achieving commercial deployment with global impact will require further cost reductions. Toward that end, the US Department of Energy’s National Renewable Energy Laboratory (NREL) and automaker General Motors (GM, Detroit, MI, US) partnered in June 2014 on a multi-year, multi-million dollar joint effort to accelerate the reduction of automotive fuel cell stack costs through fuel cell material and manufacturing research and development.
NREL and GM will focus on critical next-generation fuel-cell electric vehicle challenges, which include reducing platinum loading, achieving high power densities, understanding the implication of contaminants on fuel cell performance and durability, and accelerating manufacturing processes to achieve the benefits of increased economies of scale.
The work will be done under a Cooperative Research and Development Agreement (CRADA) between NREL and GM and takes advantage of NREL’s state-of-the-art Energy Systems Integration Facility (ESIF, Golden, CO, US). The effort includes staff collaboration and the exchange of equipment, knowledge, and materials.
“The Department of Energy has developed significant capability in fuel cell R&D, both in people and equipment, within the national lab system,” said Charlie Freese, executive director of GM’s fuel cell activities. “This arrangement provides the framework to efficiently apply the fundamental perspective and tools at NREL to address the real-world development challenges we are currently working to resolve.”
In July 2013, GM and Honda (Toyo, Japan) announced a long-term collaboration to co-develop next-generation fuel cell and hydrogen storage systems, aiming for potential commercialization in 2020. In addition, GM and Honda are working with stakeholders to advance refueling infrastructure, which is critical for the long-term viability and consumer acceptance of fuel cell vehicles.
That’s the future. For now, automakers anxious to meet looming CAFE and CO2 emission standards have spurred production of battery packs lightweighted with composites. Electric cars have lacked the driving range of their gas- and diesel-powered counterparts due, in part, to battery weight. General Motors’ Chevy Volt and Spark benefit from a new generation of 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. The Spark recently inspired development of a multimaterial battery case with significant use of composites. (Read more about the Chevy Spark’s battery enclosure by clicking “Onboard protection: Tough battery enclosure, under “Editor’s Picks,” at top right.)
The matrix binds the fiber reinforcement, gives the composite component its shape and determines its surface quality. A composite matrix may be a polymer, ceramic, metal or carbon. Here’s a guide to selection.
Fast-reacting resins and speedier processes are making economical volume manufacturing possible.
The structural properties of composite materials are derived primarily from the fiber reinforcement. Fiber types, their manufacture, their uses and the end-market applications in which they find most use are described.