Materials Used in Electric Vehicle Battery Housings: Recycling Pathways and Circular Design—A Review

Battery housings are critical structural and safety components in electric vehicles, fulfilling multiple functions related to mechanical protection, crashworthiness, thermal management, fire resistance, electromagnetic shielding, and integration of battery modules into the vehicle body. While metallic housings, particularly aluminum and steel, remain dominant in industrial applications, increasing attention is being given to composite materials as lightweight alternatives capable of improving energy efficiency and extending driving range. However, the growing use of composites in battery enclosures raises important questions regarding recyclability, end-of-life management, and compatibility with circular economy principles. This review critically examines the current state of the art in composite materials used for electric vehicle battery housings, with particular emphasis on glass- and carbon-fiber-reinforced thermoplastics, thermoset composites, sandwich structures, and hybrid multi-material systems. The paper discusses the functional requirements imposed on battery housings and analyzes how these requirements influence material selection and design strategies. Particular attention is devoted to recycling pathways applicable to composite battery enclosures, including mechanical recycling, thermal treatment, chemical recycling, and reuse-oriented approaches, as well as to the limitations associated with mixed-material assemblies, adhesives, coatings, and integrated functions. The review also addresses circular design strategies for battery housings, including design for disassembly, material traceability, modularity, and the incorporation of recycled polymers and secondary reinforcements into new housing systems. Current research gaps are identified in the integration of structural performance, fire safety, manufacturability, and recyclability within a single design framework. The analysis shows that thermoplastic composites currently offer the most promising route toward circular battery enclosures, while thermoset-based systems still face significant challenges in high-value recycling. The paper concludes by outlining future research directions required for the development of lightweight, safe and recyclable composite battery housings aligned with sustainable mobility and circular economy goals.