Automotive Design


4 Open-pored, easily shaped, electrically conductive metal foam is providing new opportunities - whether used as a gas diffusion layer in metal-air batteries or fuel cells, or as a current collector in super capacitors. Doris Schulz reports.


Foam for alternative drive concepts


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hen it comes to the development and optimisation of alternative drive concepts, the open-pored, easily shaped, electrically conductive metal


foam produced by Alantum Europe GmbH is providing new opportunities. Whether used as a gas diffusion layer in metal-air batteries or fuel cells, or as a current collector in super capacitors, the innovative material can be adapted ideally to any application, thus facilitating increased energy densities or longer service lives. The versatility of the metal foam is the result of


a manufacturing process developed specifically by Alantum. Within this process, open porous nickel foam sheets with hollow struts are produced. The pore size is defined to 450, 580, 800 and 1200µm. Subsequent annealing keeps the material flexible and easily shaped. The electrically conductive metal foam is used in significant quantities as a cathode in nickel-metal hybrid (NiMH) batteries, which are state of the art in devices such as electric and hybrid vehicles. In this application, nickel- metal foam also offers optimisation potential for increasing energy density. Namely by applying a coating of graphite or other powdered materials


suitable for energy storage to the open-pored structure in a special sintering process.


Improved power output


To achieve improvements in range and acceleration of vehicles, a great deal of research is being conducted around the world into battery technology. A promising approach is the use of metal-air batteries, whose performance can also be enhanced with the use of the porous material. As a gas diffusion layer, the foam optimises the flow rate of the metal electrode, such as zinc, with oxygen. This results in more even energy production and power output. The material is available as pure nickel foam


and as metal alloy foam for this purpose. Following production, the latter is coated with a high-alloy, application-optimised metal powder in a patented, stable process. This helps to promote resistance against aggressive atmospheres and corrosion as well as stability when exposed to temperatures of up to 1000°C.


Super capacitors


Super capacitors, as well, are capable of delivering significant improvements to electromobility. This


Fig. 1 Metal foam offers the potential for increased energy density and improved performance in both nickel- metal hybrid batteries and metal-air batteries.


Image Courtesy: Alantum 6 www.engineerlive.com


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