Lightweighting in New Energy Vehicles: A Layered Approach – Carbon Fiber Leads the High-End Market, Glass Fiber Stabilizes the Economy Model
In the lightweighting race of new energy vehicles, composite materials are staging a "tiered breakthrough"—high-end models rely on carbon fiber reinforced polymer (CFRP) for core performance, while economy models depend on glass fiber reinforced polymer (GFRP) for cost control and efficiency improvement. This tiered strategy is shifting the industry from "single material competition" to "system efficiency optimization," reshaping the competitive landscape of automotive materials.
High-end models: Carbon fiber supports the "performance ceiling"
With a specific strength five times that of steel and a density only one-third that of aluminum, carbon fiber has become a "weapon" for high-end models to break through lightweighting bottlenecks, and its application has moved from single-point trials to multi-scenario penetration.
In terms of body structure, the BMW i7's Carbon Core steel-carbon hybrid body reduces the weight of the body-in-white by 30% compared to traditional steel bodies, while increasing torsional stiffness by 20%; the NIO ET7's carbon fiber roof is integrally formed using RTM technology, reducing weight by 42% compared to aluminum alloys, and the 0.1mm-level fiber layup precision ensures uniform stress distribution on curved surfaces.
Lightweighting of battery systems also relies heavily on carbon fiber. CATL's carbon fiber battery casing, developed in collaboration with SGL Carbon, uses T700-grade continuous fibers and epoxy resin. This not only meets IP68 waterproofing standards but also reduces weight by 40% compared to aluminum alloy casings, while increasing battery pack energy density by 12%. Tesla is further exploring the integration of carbon fiber current collectors and structural components in its 4680 battery technology, which is expected to further reduce battery pack weight by 15%.
Manufacturing processes are also being upgraded. Robotic Automated Placement (AFP) technology achieves ±0.5° layup angle control. One automaker used it to produce carbon fiber door panels, increasing yield from 75% to 98% and reducing single-piece production cycle to 8 minutes. Napan Technology's CF/PEEK thermoplastic carbon fiber achieves 100% recyclability through laser welding, reducing repair costs by 60%.
Economy Cars: Fiberglass Leads the Way in Cost-Effectiveness
With costs only 1/10th that of carbon fiber and high molding efficiency, fiberglass has become the "main force" in lightweighting economy cars, rapidly being implemented in battery packs, body panels, and other applications.
The BYD Seal 07's battery pack uses an SMC composite material top cover + high-strength aluminum lower shell, reducing weight by 18% and material costs by 25% compared to an all-aluminum structure. The Tesla Model Y's battery pack end plates are molded using short-cut fiberglass, enabling rapid manufacturing of complex irregular structures and reducing unit costs by 30% compared to aluminum alloys.
The performance of body panels is also improving. The Geely Xingyue L's hood uses GMT fiberglass felt-reinforced thermoplastic, with a honeycomb sandwich design that reduces weight by 35% and improves dent resistance by 20%, easily meeting the C-NCAP five-star safety standard. The XPeng G3's door interior panels use long fiberglass-reinforced polypropylene, 3D printed pre-molded and injection molded in one piece, reducing weight by 52% compared to traditional steel.
Technological innovation is also focusing on cost reduction and recycling. Shandong Fiberglass's 24K large-tow glass fiber reduces costs by 15% through tank furnace drawing technology, and increases interfacial shear strength by 25% after surface modification. Chongqing International Composite Materials' chemical depolymerization production line can regenerate waste components into high-performance materials with a recycling rate of 95%, reducing costs by 40% in closed-loop applications.
Behind the tiered applications: Synergy of performance, cost, and recycling
This strategy of "using carbon for high-end and glass for economical" is fundamentally about precisely matching material performance with cost. Data from the Chinese Society for Composite Materials shows that the two form a gradient in strength, density, and cost, perfectly covering the needs of different vehicle models.
The process routes also have different focuses: high-end models use autoclave curing + AFP fiber placement, reducing the production cycle of carbon fiber monoshells for vehicles like the BMW i8 to 2 hours; economical models use compression molding + automated cutting, with one automaker's glass fiber battery cover production line using AI detection to reduce the defect rate from 8% to 1.5%, achieving a capacity of 50 pieces/hour. The advantages of full life-cycle efficiency are becoming increasingly apparent: Carbon fiber vehicles reduce weight by 10%, increasing range by 6-8% and extending corrosion resistance by 3 times, supporting the performance premium in the high-end market; the cost of composite materials per unit in fiberglass vehicles can be controlled within 5,000 yuan, firmly securing cost-effectiveness in the economy market.
The Future: Material Integration and Circular Upgrading
Going forward, the application of composite materials will become even more "flexible." The chassis of the GAC AION S uses an aluminum-glass hybrid composite, with key nodes reinforced by carbon fiber, resulting in a 28% weight reduction compared to all-steel and an 18% lower cost than all-aluminum. This "carbon fiber for core components, glass for secondary components" approach is becoming a new choice for mid-range vehicles.
Intelligent integration is also accelerating: Carbon fiber battery casings with embedded fiber optic sensors can monitor stress in real time and provide early warning of thermal runaway; fiberglass components coated with graphene improve heat dissipation efficiency by 30% and are compatible with 800V high-voltage platforms.
The circular economy is also a major focus. Driven by the EU's new Battery Law, HRC's low-temperature carbon fiber recycling process retains 95% of the strength of recycled fibers while reducing costs to 60% of virgin materials, with a projected penetration rate exceeding 30% by 2030. Glass fiber achieves 100% recycling through physical crushing and reprocessing; one automaker uses it to reduce carbon emissions by 12,000 tons annually.
Lightweighting in new energy vehicles is no longer simply a matter of "changing materials." The phased application of carbon fiber and glass fiber, through three-dimensional optimization of performance, cost, and recyclability, is propelling the industry towards "full life-cycle carbon neutrality"—a breakthrough in materials technology and an inevitable transformation of the automotive industry.