Automotive Design
Fig. 2. Used as a gas diffusion layer in fuel cells, metal alloy foam provides optimised equal distribution of the gas which allows increasing the power density across the entire membrane surface.
Image Courtesy: Alantum
is thanks to their ability to compensate voltage peaks that occur during acceleration and braking, which in turn helps to lengthen the durability of batteries and fuel cells. As the so called ‘supercaps’ release and absorb energy more quickly than batteries, they do not have such a high energy density.
In contrast to conventional methods, whereby carbon is applied to a film, the foam was infiltrated with molybdenum- and vanadium-nitride as an active material. In comparison to carbon, these materials have an energy
density that is two to three times higher. Thanks to the special structure and large surface of the foam, it is possible to apply sufficient active material to achieve a two to three-fold increase in the energy density of the super capacitor.
Gas diffusion
Metal alloy foam can also offer a number of advantages when used as a gas diffusion layer in fuel cells. On the one hand it provides optimised equal distribution of the gas and the resulting increase in power density across the entire membrane surface. On the other hand, the material can be sintered to the bipolar plates in order to achieve a direct electrical connection. An additional advantage is the ability of the metal alloy foam to resist the very aggressive atmospheres that typically exist in fuel cells. For use as a gas diffusion layer, the material can be coated
Fig. 3. Used in conjunction with a molybdenum-vanadium-nitride coating, metal foam can deliver a two to three-fold increase in the energy density in super capacitors.
Image Courtesy: IFAM
Whether or not this is an area that can be improved upon with the use of foam material was one of the themes of the ‘Alternative Energy Technologies for Transportation (AETT)’ research project carried out by the Fraunhofer Society in collaboration with the University of Michigan and the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) and Alantum Europe as the foam supplier. The metal alloy foam was used as a current collector.
with conventional alloys such as stainless steel alloy 316L and CroFer as well as with new, application-optimised metal powders.
Alantum currently produces around four million square
metres of nickel foam in China annually. This is in addition to 500,000 square metres of metal alloy foam which are produced in Korea. In order to further optimise the material for applications in electromobility, the Munich-based company is working closely with IFAM in Dresden. Here, a research laboratory is also available in which tests may be conducted and samples can be produced. ●
Alantum Europe GmbH, Munich, Germany.
www.alantum.com
www.engineerlive.com 7
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