As the automotive industry transitions towards electric vehicles (EVs), the need for innovative materials becomes paramount. EVs, generally heavier than traditional vehicles, face unique challenges such as increased tire wear and the critical demand for motor efficiency. Thermoset composites have emerged as an ideal solution, offering a combination of strength, weight reduction, and thermal management. However, their application requires careful consideration of several key factors to maximize their benefits in EV design.
Weight Reduction
One of the primary considerations in using thermoset composites is their potential for significant weight reduction. EV batteries are notably heavy, with the electric Hummer’s battery only 22 pounds lighter than a Toyota Corolla. Therefore, other vehicle components must be as light as possible to offset this weight.
Thermoset composites have demonstrated their efficacy in reducing weight in various industries. For example, carbon nano-reinforced polymers are 30% lighter than conventional materials used in aerospace applications, contributing to more fuel-efficient planes. Applying these materials to EV components could yield similar results, enhancing overall vehicle efficiency.
Different thermoset composites vary in weight. Carbon fiber-reinforced polymers are generally lighter and thus more suitable for automotive applications than those using glass fibers. Additionally, epoxies offer a higher strength-to-weight ratio compared to polyesters but come with higher corrosion susceptibility, introducing specific maintenance concerns.
Heat Dissipation
While weight reduction is crucial, thermoset composites must also manage heat effectively. Although electric motors do not generate as much heat as internal combustion engines, they still produce significant heat that can warp conventional plastics and reduce efficiency. Effective heat dissipation is essential for maintaining optimal motor performance and longevity.
Thermoset composites enable the creation of structures that dissipate heat more efficiently than traditional methods. For instance, researchers at the Fraunhofer Institute for Chemical Technology ICT have used flat cooling wires within a polymer housing to dissipate over 80% of heat losses. This lightweight housing allows for more efficient movement and heat transfer without the need for liquid coolants.
The choice of materials also impacts thermal management. Silicone-based composites are generally preferred for their high thermal stability, enabling efficient routing of waste heat.
Structural Strength
The use of lightweight and heat-dissipating materials must not compromise the structural integrity of EV components. Strength remains a critical factor, as failure of any part can lead to severe consequences. Thermoset composites must therefore offer sufficient tensile strength to withstand the mechanical stresses of automotive applications.
Glass fibers, which constitute 90% of thermoset reinforcements, offer tensile strengths up to 500,000 psi, which, while respectable, is less than that of carbon fiber. Carbon fiber-reinforced polymers provide a higher strength-to-weight ratio, maintaining structural stability without adding significant weight. However, carbon fiber can be brittle in certain directions, making it less suitable for all applications.
A strategic approach involves mixing and matching reinforcements based on the specific component requirements. Carbon fiber is ideal for high-intensity but low-impact parts, such as motor housings, while Kevlar reinforcements are more reliable for exterior components that need to withstand more impact.
Form Factor
The size and shape of thermoset composite parts can influence their effectiveness. Designing components with appropriate form factors can compensate for some material weaknesses or amplify their strengths. Thick shielding, for instance, may protect sensitive circuitry from heat and stress but can be space-consuming and heavy.
Space constraints are particularly challenging in EV design, where every gram counts. Using lighter, more resilient composites can help optimize space and weight. For example, manufacturers like Marian Inc. have used neoprene and silicone-based thermosets to create flexible yet durable components that maintain compression and alleviate stress.
Sustainability
Sustainability is a key selling point for EVs, as they are marketed as eco-friendly alternatives to fossil fuel vehicles. However, ensuring that all vehicle components, especially plastics, are environmentally sustainable poses a significant challenge.
Designing EV parts to last longer can reduce waste, as durable thermoset housings can withstand repeated pressures and resist degradation, thus minimizing plastic disposal. Recent advancements also offer eco-friendly alternatives. For example, SABIC has developed methods to recycle plastics without property loss by