Mechanical characterizations on biobased FMLs, being developed for battery boxes, before and after ageing

Abstract

Abstract This paper reports the activities carried out under project FENICE (Upscaling, KAVA 9, EIT Raw Materials, www.Fenice-composites.eu, 2022-2025) about improving fire resistance of electric cars batteries, in particular through the development of Fiber Metal Laminates (FML) battery boxes. The aim of this study is to analyse the corrosion behaviour of FML based on bio-based and closed loop recyclable prepregs, in typical ageing conditions (thermal ageing, neutral and cupric acetic salt spray). FML degradation, evaluated in term of residual tensile strength after ageing, along with surface corrosion is remarkably low, and also resistance to humid environment seems satisfactory. However proper inorganic surface finishing is needed, since otherwise typical automotive tests, such as salty spray chamber ageing, cannot be passed in term of corrosion resistance requirements. The project is studying surface vitrification with sol-gel formulations, since traditional painting, based on organic polymers could ensure aluminium corrosion resistance, but would inevitably decrease fire resistance, while Cr-plating is not environmentally friendly, because of its higher carbon footprint and since it would make direct aluminium recyclability impossible, so. These advanced treatments were, up to now, not compatible with the adoption in the mass production, but things are rapidly changing, following the green transition that is currently bringing a number of small revolutions in the manufacturing sector.