Electric Vertical Takeoff and Landing (eVTOL) aircraft are poised to redefine urban mobility, offering rapid, quiet, and emission-free travel across congested cities. As development accelerates toward commercial deployment, one of the most pressing engineering challenges is thermal management in the power systems that propel these aircraft. The high power densities required for takeoff, cruise, and landing generate intense heat that must be dissipated rapidly to protect sensitive electronics, maintain efficiency, and ensure safety. Traditional cooling methods — aluminum heat sinks, forced air, and liquid cooling loops — are reaching their limits as power densities climb. This has sparked a wave of innovation in materials specifically engineered for superior heat dissipation. From atomically thin carbon layers to porous crystalline frameworks, emerging materials are set to transform how eVTOL power systems stay cool under pressure.

Thermal Demands of eVTOL Power Systems

eVTOL aircraft operate under conditions that push conventional thermal management to its breaking point. The power electronics — inverters, converters, motor controllers — handle currents that can exceed hundreds of amperes, especially during vertical takeoff and landing when thrust demand is highest. Battery packs, typically lithium-ion or emerging solid-state chemistries, also generate significant heat during rapid charge and discharge cycles. Unlike ground vehicles, eVTOLs cannot rely on natural airflow at low altitudes or during hover. The compact packaging required to meet weight and space constraints further exacerbates heat buildup, creating hot spots that degrade performance and shorten component lifespan.

Thermal runaway in batteries, overheating of insulated-gate bipolar transistors (IGBTs) in inverters, and delamination of printed circuit boards are real risks. The Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA) have established stringent certification standards for thermal behavior, requiring that power systems maintain safe operating temperatures under all flight conditions, including failure scenarios. Meeting these standards demands materials with thermal conductivities far beyond what traditional aluminum (around 200 W/m·K) or copper (400 W/m·K) can provide, especially when weight and volume are constrained.

Material Innovations for Enhanced Heat Dissipation

Researchers and manufacturers are exploring a spectrum of advanced materials that leverage unique physical properties to move heat away from critical components more efficiently. These materials range from ultrathin carbon allotropes to engineered composites that harness phase change or capillary action.

Graphene and Graphene-Based Composites

Graphene, a single-atom-thick sheet of carbon, is celebrated for its extraordinary thermal conductivity — measured at up to 5,000 W/m·K under ideal conditions. In practice, graphene films and flakes, when incorporated into polymer matrices or as stand-alone coatings, can dramatically enhance heat spreading. For eVTOL applications, graphene-enhanced thermal interface materials (TIMs) reduce the thermal resistance between a heat-generating chip and a heatsink. Graphene foams and aerogels also show promise as lightweight, high-surface-area substrates for heat exchangers. However, challenges remain: consistent large-scale production of defect-free graphene is costly, and aligning graphene flakes in composites to maximize conductivity requires careful processing. Companies such as Graphenea and XG Sciences are advancing manufacturing techniques, while academic groups at MIT and the University of Manchester continue to explore hybrid graphene-polymer films that combine flexibility with high conductivity. Recent studies have demonstrated that adding just 1–5% graphene by weight to epoxy can double its thermal conductivity, a meaningful gain for potting and encapsulation compounds used in eVTOL power modules.

Carbon Nanotubes (CNTs)

Carbon nanotubes — cylindrical molecules with walls of graphene — also offer exceptional thermal conductivity, with individual single-walled CNTs reaching values near 3,500 W/m·K. In bulk form, CNT arrays and buckypapers can be used as thermal interconnects or as fillers in TIMs. Their high aspect ratio and mechanical strength make them particularly attractive for conformal cooling layers that fit around irregular geometries in inverters or battery packs. Research groups at Rice University and Tsinghua University have developed methods to grow vertically aligned CNT forests that act as thermal superhighways between a chip and its heatsink, reducing interface resistance by orders of magnitude. For eVTOL, where vibration and thermal cycling are constant, the mechanical resilience of CNTs is a key advantage over traditional solders or greases.

Diamond-Based Materials

Synthetic diamond, produced by chemical vapor deposition (CVD), has a thermal conductivity exceeding 2,000 W/m·K — five times that of copper — along with excellent electrical insulation properties. Diamond substrates and heat spreaders are already used in high-power lasers and radio-frequency amplifiers, and they are now being evaluated for eVTOL power electronics. Diamond’s extreme hardness and low coefficient of thermal expansion make it an ideal substrate for gallium nitride (GaN) and silicon carbide (SiC) power devices, which are themselves more efficient than traditional silicon but generate concentrated heat. Companies such as Element Six (part of the De Beers Group) and IIa Technologies produce CVD diamond wafers in sizes suitable for mounting multiple power dies. The primary barriers are cost — diamond wafers can be hundreds of dollars per square centimeter — and the difficulty of integrating diamond with standard packaging processes. However, as eVTOL production scales, costs are expected to decrease, making diamond a viable option for premium thermal management.

Phase Change Materials (PCMs)

Phase change materials provide a different approach: instead of merely conducting heat, they absorb it during a phase transition, typically from solid to liquid. By integrating PCMs into battery packs or power electronics enclosures, engineers can create thermal buffers that soak up transient heat spikes — for instance, during a rapid climb or emergency descent — and release the heat slowly during lower-demand periods. Common PCMs for eVTOL include paraffin waxes, salt hydrates, and fatty acids, with melting points tailored between 40°C and 80°C. More advanced options use metallic alloys or organic eutectics with higher latent heat capacities. The key to effectiveness is encapsulation: PCMs must be sealed in microcapsules or embedded in a porous matrix to prevent leakage when molten. Companies like Phase Change Energy Solutions and Entropy Solutions offer commercial PCM composites that can be integrated into battery module housings or heatsink fins. Research at the University of Maryland has shown that adding a graphite foam infiltrated with PCM can reduce peak battery temperatures by 15–20°C during aggressive discharge cycles.

Metal-Organic Frameworks (MOFs)

Metal-organic frameworks are a class of porous crystalline materials with an immense internal surface area — up to 7,000 m² per gram. While primarily studied for gas storage and catalysis, MOFs are now being explored for thermal management due to their ability to rapidly transfer heat through their pore networks and to adsorb and desorb molecules that carry heat away. Some MOFs exhibit phase-change-like behavior, absorbing large amounts of heat during desorption of water or other guest molecules. For eVTOL, MOF coatings on heat exchanger surfaces could enhance convective cooling by promoting nucleate boiling, or they could serve as thin-film thermal regulators that respond to temperature changes. Research is still early-stage — groups at UC Berkeley and the University of Cambridge are synthesizing MOFs with record thermal conductivities and testing them in microelectronic cooling demonstrations. The tunability of MOF chemistry allows customization of thermal properties, but challenges include stability under humid conditions and scalable synthesis.

Liquid Metal Thermal Interfaces

Liquid metals — such as gallium, indium, and tin alloys — offer thermal conductivities above 30 W/m·K in the liquid state, far surpassing conventional thermal greases (0.5–5 W/m·K). Unlike solid TIMs, liquid metals can flow into microscopic gaps, ensuring intimate contact between surfaces. For eVTOL power modules, gallium-based liquid metal TIMs are being tested to replace solders and thermal pastes in high-heat-flux applications. One concern is electrical conductivity: liquid metals can short-circuit components if they leak. Therefore, precise dispensing and robust containment are required. Companies like Indium Corporation produce preform sheets and dispensable alloys specifically for power electronics. Recent advances in liquid metal encapsulation (e.g., using silicone or elastomeric barriers) have reduced leakage risks, making them more practical for aerospace environments subject to vibration and thermal cycling.

Comparative Performance and Selection Criteria

Choosing the right material depends on the specific thermal challenge within the eVTOL power system. For steady-state heat spreading over large areas, graphene films or CVD diamond wafers offer the highest conductivities, but at a cost premium. For eliminating interface resistance between a GaN transistor and its heatsink, liquid metal or CNT arrays provide the lowest thermal impedance. For managing transient spikes, PCM composites and MOF-based thermal buffers deliver passive temperature regulation without active cooling loops. A multi-material approach is often optimal: for example, a diamond substrate beneath a power chip, coupled with a graphene TIM, and a PCM reservoir embedded in the nearby structure to absorb peak loads. Weight is another critical factor — graphene foams and CNT buckypapers are among the lightest options, while diamond is denser. Aerospace certification also imposes long-term reliability requirements: materials must withstand thousands of thermal cycles without degradation. Accelerated aging tests at Boeing and Airbus have highlighted the need for robust adhesion and corrosion resistance in hybrid composites.

Integration Challenges and Manufacturing Scalability

Lab-scale successes do not automatically translate to production lines. Many of these emerging materials — especially graphene, MOFs, and CVD diamond — require specialized equipment and process conditions that are expensive and slow. For eVTOL manufacturers to adopt them, costs must fall and throughput must rise. Progress is being made: chemical vapor deposition of diamond has moved from small research reactors to batch systems capable of coating 4-inch wafers, and roll-to-roll production of graphene films is now commercially available. Still, integrating these materials into existing power module packaging (e.g., wire bonding, soldering, encapsulation) often requires redesign of interfaces and assembly processes. Thermal interface materials that are solid at room temperature but melt during operation (like certain PCM composites) must be contained with reliable gaskets or adhesives. MOF coatings need to be grown directly on heat transfer surfaces under controlled conditions, which adds manufacturing steps. Despite these hurdles, partnerships between material suppliers and eVTOL developers — such as Joby Aviation’s collaboration with thermal management firms — are accelerating integration. NASA’s Advanced Air Mobility program is actively funding research into these very topics, recognizing that thermal solutions are a bottleneck for certification.

Future Research Directions

Several promising directions are emerging that could further improve eVTOL thermal management. One is the development of hybrid thermal management systems that combine multiple materials in a single integrated package — for instance, a skin of graphene composite wrapped around a PCM-filled battery module, with diamond heat spreaders embedded at hot spots. Another area is active control of thermal properties using tunable materials like shape-memory alloys or electrically switchable PCMs that change their conductivity or latent heat on demand. The concept of thermal metamaterials — engineered structures that route heat around obstacles or concentrate it at specific points — could be applied to eVTOL circuit boards to protect sensitive components. Machine learning is also playing a role: algorithms can now optimize the arrangement of different TIMs and heat sinks within a power module to minimize thermal resistance and weight simultaneously. Finally, as eVTOL designs move toward distributed electric propulsion with multiple small motors and inverters, the need for lightweight, scalable thermal materials becomes even more acute. The U.S. Department of Energy’s vehicle technologies office has outlined roadmaps that include thermal management milestones for electric aviation, noting that materials with conductivities above 1,500 W/m·K and densities below 2 g/cm³ are targets for 2028.

The convergence of materials science, aerospace engineering, and manufacturing innovation is steadily turning these high-performance heat dissipation materials from lab curiosities into practical components. As eVTOL developers race toward certification and production, the ability to manage heat effectively will be a decisive factor in vehicle safety, range, and operational cost. Early adopters of graphene-enhanced TIMs, diamond substrates, and PCM buffers are likely to gain a competitive edge. With sustained investment and cross-industry collaboration, the thermal challenges that once seemed insurmountable will become solved problems, clearing the way for the widespread adoption of urban air mobility. EASA’s evolving certification framework continues to incorporate thermal management requirements, underscoring its critical role in the future of flight.