UC Berkeley

Abstract The electric vehicle (EV) industry is growing rapidly; however, compared to conventional automobiles, the increased weight of EVs contributes to their more limited range. To reduce total EV weight, higher-end vehicles use materials such as aluminum, which are more costly and energy-intensive than steel. This presents a challenge to the industry: there is a need to transition toward both lightweighting and material circularity. Improved materials are needed not only to reduce weight and improve efficiency but also to facilitate reclamation of metals and polymers from end-of-life vehicles. This study provides and demonstrates a framework for evaluating lightweight polymer alternatives for conventional EV components from a circularity perspective. The study identifies replacement materials for bumpers, door panels, interior consoles, and battery enclosures by evaluating material properties, environmental impacts, and economic metrics. Next, the study explores the battery enclosure as a deep-dive case study, establishing four scenarios: steel (S1), carbon fiber reinforced epoxy (S2), glass fiber reinforced epoxy (S3), and glass fiber reinforced polydiketoenamine (PDK) resin (S4). The life-cycle assessment and techno-economic analysis include recycling processes for the various scenarios. Results indicate that current materials in bumpers (polypropylene) and interior consoles (ABS) are functionally, economically, and environmentally favorable, while polymer composites such as fiber reinforced PDK can improve upon some economic and environmental metrics for door panels and battery enclosures relative to current materials. Results show that battery enclosure replacement demonstrates the highest potential for weight reduction and improved circularity without compromising durability. Specifically, the S1 and S4 scenarios achieve comparatively lower levelized recycling costs (LRCs). Between S1 and S4, use-phase CO 2 e emissions are lower for S4 due to the lighter-weight PDK composite material. The viability of PDK composites depends on recycling practices (dismantling vs. non-dismantling) and the final selling price of recycled PDK resin. Dismantling enables greater overall recovery of battery materials, achieving an LRC of $93 per enclosure, whereas not dismantling increases the LRC to $188. If recycled PDK can sell for prices equivalent to higher-cost virgin PDK, the LRC per enclosure can be -$297 to to -$175. This study offers a framework for systematically evaluating EV lightweighting and circularity strategies using polymer composites.