36 September/October 2025 | E-Mobility Engineering However, this requires expertise in materials, tool design and process optimisation, in addition to materials and process modelling. While thermoplastics have long been used in manufacturing, the cost, complexity and processing challenges have limited their application to large components. Improvements in advanced materials, coupled with the machinery, moulding, tooling design and processing expertise across the value chain, make thermoplastic moulding of large parts more feasible for more components, and battery casings and trays are the first areas to exploit such technology. Using thermoplastic moulding allows for cost and process efficiency by using competitive tooling, consolidating parts and simplifying manufacturing, post-processing and assembly steps. It has faster injection moulding cycle times compared with metal casting or thermoset processing, as well as greater design freedom to achieve more complex geometries and functional integration that are difficult with metal stamping or casting. This enables simplified product architecture with better designs for disassembly, sorting and recycling as well as weight and mass reduction while meeting strength and stiffness requirements. The strength in thermoplastic materials is typically achieved using reinforcing agents such as glass fibres or talc, combined with thermoplastic polymers such as PP, PC, PBT, PET or blends of these. This combination delivers the desired strength at the material level before being moulded into large battery enclosures. For fire retardancy, various flameretardant ingredients are integrated into the thermoplastic compounds to meet specific safety requirements. While the exact formulations are proprietary, these include halogenated, nonhalogenated, intumescent and options for non-intentionally added PFAS (per- and polyfluoroalkyl substances). These are selected based on resin type and customer requirements. Some suppliers use a database of materials through internal research and extensive prototyping of large battery components. To enable largescale production, materials with a low viscosity or high flow are needed to fill the larger dimensions using existing injection moulding equipment in the supply chain. A key advantage of thermoplastics is that the materials can be optimised for the process conditions, allowing these components to be manufactured without significant new capital investment. A large battery enclosure prototype demonstrates proof-ofconcept across multiple manufacturing methods for plastics, including injection moulding, compression moulding and thermoforming. Using the thermoplastic approach cuts weight by 20% versus that of an all-aluminium design. Thermoplastic enclosures have been proven in both virtual and physical impact tests to meet and exceed customer requirements, even in the critical side-pole crash scenario. The high impact toughness makes the material resilient against mechanical stress and external forces. This is particularly valuable in crash scenarios or harsh operating environments, where structural integrity must be maintained. Another key advantage is the design freedom and flexibility thermoplastics offer. Unlike metals, they allow for the creation of complex geometries and integrated features in a single moulded piece. This not only simplifies assembly but also reduces part count Tech focus | Battery pack materials A battery case prototype using large-area thermoplastics. The multi-material enclosure features a thermoplastic/organosheet sandwich cover panel, an all-thermoplastic tray and a metal underbody panel. Flame retardant (FR) Stamax long-glass-fibre polypropylene (LGF-PP) is used for the thermoplastic components (Image courtesy of SABIC) Material PA6D-LFT composite PP D-LFT composite Aluminium Steel Tensile strength [MPa] 361,0 288 340 600 Strength to weight ration [MPA per g/cm3] 201 175 126 76 Comparison of composite thermoplastic with aluminium and steel (Courtesy of Kautex Textron)
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