TAGS: Electrical & Electronics Metal Replacement New Energy Solutions
Scientists at the Fraunhofer Institute for Structural Durability and System Reliability LBF have developed a lightweight battery pack that exclusively uses fiber-plastic composites. In this way, the weight has been reduced by 40 percent compared to aluminum housings. This design not only reduces the moving mass of the e-mobile, but also increases its range and dynamics thanks to additional integrated functions. Because the battery pack is manufactured in a specially developed, highly efficient process and has a specific structure, it can be produced very cheaply.
New Highly Efficient Hybrid Process
The research team at Fraunhofer LBF has produced a lightweight battery pack housing made of continuous fiber-reinforced thermoplastics in a sandwich structure and used a novel process that combines highly efficient foam injection molding with thermoplastic FRP. This so-called in-situ FRP sandwich process enables the production of finished lightweight battery housings within around two minutes without post-processing.
In addition, functions such as the thermal insulation capacity of the manufactured battery housing can be integrated in the same process step, which would not be possible with classic metallic construction materials and manufacturing processes.
Cost-effective and Lightweight Battery Housing
The lightweight battery pack is made up of a housing and cell holders made of fiber composite materials. The housing consists of UD tapes from SABIC, which are first woven and then consolidated. The checkerboard laminate resulting from this process step is then preformed and placed on both sides in a specially developed hybrid foam injection molding tool.
The targeted injection of an integral foam between the laminates creates the housing with fiber composite cover layers and a foam core. This load-bearing sandwich construction leads to the highest weight-specific mechanical properties and at the same time reduces the material consumption of the fiber composite laminates used. The associated reduction in material costs, in combination with the very short cycle times, leads to low component costs. In addition, this method is also suitable for covering other areas of application and their requirements, since a wide variety of fiber composite materials and types of plastic can be combined and used.
Replacing Metal in Battery Packs
Due to the large number of battery cells required, battery packs for electric vehicles are currently very heavy if the required long ranges beyond 500 kilometers are to be achieved. The mechanical structure around the cells, such as the cell holder and the housing, which is currently made of aluminum or steel, add up to the total weight of several hundred kilograms in addition to the electrical components.
Depending on the vehicle design, the mechanical structure of the battery pack can make up more than 30 percent of its total mass. "
In order to increase the gravimetric energy density without having to change the cell technology, it makes sense to build the necessary mechanical structures for the battery pack more easily," emphasizes Dr. Felix Weidmann, Fraunhofer LBF.
In addition to the process for the efficient production of the battery housing as a fiber composite sandwich construction, the Darmstadt researchers also developed simulation-based methods with which the production quality can be predicted and thus the preliminary design and production can be significantly simplified.
Source: Fraunhofer LBF