3D-Printed Porous Structure Cuts EV Battery Overheating Risk by 45%
In a breakthrough that could reshape electric vehicle (EV) thermal safety standards, researchers in China have developed a novel battery cooling method that dramatically reduces temperature gradients and suppresses thermal runaway risks in high-performance lithium-ion packs. The innovation centers on embedding phase change material (PCM)—commonly paraffin wax—into a copper-based porous scaffold, creating a hybrid thermal management system that outperforms conventional PCM-only designs by wide margins.
The solution, tested under aggressive 4C discharge conditions typical of fast-charging and high-speed driving scenarios, lowered peak battery temperatures by 2.1% in the first 12 minutes of operation while slashing the gap between maximum and average cell temperatures by 45.5%. Even more critically, it reduced inter-cell temperature variance by 34.1%, a key metric for pack longevity and safety. These gains address one of the most persistent engineering challenges in EV development: maintaining thermal uniformity across densely packed battery modules without adding excessive weight, complexity, or cost.
For automakers racing to deliver longer-range, faster-charging EVs, thermal management has become a bottleneck. As energy densities climb—now exceeding 300 Wh/kg in premium cells—the risk of localized overheating intensifies. Traditional air-cooling systems struggle to keep pace, while liquid-cooling architectures add pumps, hoses, coolant reservoirs, and control units that increase both mass and failure points. Passive PCM-based systems offer simplicity and reliability but suffer from inherently low thermal conductivity, often below 0.2 W/(m·K) for organic PCMs like paraffin. This limitation can lead to heat accumulation in the core of the pack, especially during repeated high-load cycles.
The new approach, detailed in a peer-reviewed study, sidesteps these trade-offs by integrating the PCM into a high-conductivity porous copper matrix. The structure acts as both a thermal highway and a mechanical cage: it accelerates heat diffusion from hot spots while physically containing the PCM during its liquid phase, eliminating leakage and structural collapse risks that have plagued earlier PCM implementations.
“The porous architecture doesn’t just support the PCM—it transforms it,” said lead researcher Wang Tiansi of Jiangsu University’s School of Automotive and Transportation Engineering. “By maximizing surface contact between the copper skeleton and the phase change material, we create thousands of micro-conduction paths that pull heat away from cells far more efficiently than bulk wax ever could.”
The team validated their design using a 5S4P cylindrical cell pack—20 cells arranged in five series-connected strings of four parallel units each—simulating real-world geometry used in vehicles from Tesla to NIO. Under 4C discharge (a rate that fully depletes a 2,500 mAh cell in 15 minutes), the porous-PCM system maintained all cells within a 4°C window, well below the 5–7°C threshold where performance degradation and safety concerns escalate.
In contrast, packs cooled only by air exhibited hotspots exceeding 52°C, with edge-to-center differentials nearing 9°C. Even pure PCM packs, while better than air, showed significant thermal stratification: the central cells ran consistently hotter due to slower heat migration through the low-conductivity wax. This “thermal bottleneck” creates a dangerous feedback loop—hotter cells degrade faster, increasing internal resistance and generating even more heat during subsequent cycles.
The porous copper scaffold disrupts this cycle. With an effective thermal conductivity of 44.5 W/(m·K)—over 200 times that of liquid paraffin—it rapidly redistributes heat across the entire pack volume. Simulations revealed that during phase transition, the PCM in the porous system melts more uniformly, avoiding the directional melting front observed in bulk PCM, which tends to start at the hottest point (usually the pack center) and propagate outward. That uneven transition not only creates thermal stress but also allows liquid PCM to migrate, potentially pooling in low spots and leaving other areas under-cooled.
By locking the PCM within nanoscale pores, the new design prevents this migration. The capillary forces within the copper matrix hold the liquid wax in place, ensuring consistent thermal contact with every cell surface. This containment also solves a long-standing durability issue: in conventional PCM systems, repeated melting and solidification can cause material fatigue, leading to cracks, leaks, or even complete structural failure over hundreds of cycles. The porous framework absorbs mechanical stresses, preserving integrity over the battery’s full lifecycle.
From a manufacturing standpoint, the system remains elegantly simple. No pumps, valves, or external coolant loops are required. The entire thermal interface can be pre-assembled as a modular insert, compatible with existing battery pack assembly lines. While copper adds some mass, its high conductivity means less material is needed compared to aluminum-based alternatives, and the elimination of liquid-cooling hardware often results in net weight savings.
Industry experts see immediate applicability. “This isn’t just a lab curiosity—it’s a drop-in upgrade for passive thermal systems,” said a senior battery engineer at a European EV startup, who reviewed the findings. “For entry-level or mid-range EVs where cost and simplicity are paramount, this could be a game-changer. It gives you 80% of liquid cooling’s performance with 20% of the complexity.”
The technology also aligns with global sustainability goals. Paraffin wax is non-toxic, chemically stable, and recyclable. Copper is among the most efficiently recycled metals on Earth, with recovery rates exceeding 90% in automotive applications. Unlike glycol-based coolants, which require periodic replacement and pose environmental hazards if leaked, the porous-PCM system is sealed for life.
Looking ahead, the research team is exploring alternative scaffold materials, including lightweight metal foams and carbon-based composites, to further reduce weight for premium performance vehicles. They’re also investigating hybrid configurations that combine the porous-PCM layer with minimal liquid cooling channels for ultra-high-performance applications, such as electric supercars or commercial aviation.
Regulatory bodies may take note as well. With the U.S. National Highway Traffic Safety Administration (NHTSA) and the European Union tightening thermal runaway propagation standards—requiring packs to contain a single-cell failure without cascading—the ability to maintain sub-5°C differentials could become a compliance advantage. Current liquid-cooled packs often meet these standards through extensive cell-to-cell fire barriers, which add cost and reduce energy density. A more thermally uniform pack may require less insulation, freeing up space for additional cells.
Investors in the EV supply chain should watch for commercialization signals. Co-author Wang Wanlin is affiliated with VonerGy Technology Limited (Zhenjiang), a major Chinese battery manufacturer supplying cells to global OEMs. While the paper doesn’t disclose IP filings, the involvement of an industry partner suggests a clear path to production. If scaled successfully, the technology could be integrated into next-generation battery modules as early as 2027.
For consumers, the benefits translate into real-world advantages: longer battery life (due to reduced thermal stress), faster charging capability (as thermal limits are less restrictive), and enhanced safety—particularly in hot climates or during mountain driving, where sustained high loads test thermal systems to their limits.
Critically, the approach doesn’t require rethinking battery chemistry. It works with existing NMC, LFP, and even emerging solid-state cells, making it a versatile enabler rather than a niche solution. As the EV market matures and competition shifts from range anxiety to total cost of ownership and reliability, innovations that extend pack life while reducing system complexity will gain outsized value.
In an era where every gram and every degree Celsius matters, this porous-PCM architecture offers a rare combination: significant performance gains without added operational overhead. It exemplifies the kind of systems-level engineering that will define the next decade of electrified mobility—not through radical reinvention, but through intelligent integration of proven materials in novel configurations.
As global EV sales surpass 14 million units annually and battery production scales into the terawatt-hour range, thermal management solutions that are safe, scalable, and sustainable will separate leaders from laggards. This research from Jiangsu University and VonerGy points toward a future where overheating is no longer the Achilles’ heel of electric propulsion—but a solved problem, quietly managed by a sponge of copper and wax.
Wang Tiansi, Liu Haoran, School of Automotive and Transportation Engineering, Jiangsu University, Zhenjiang 212013, China; Wang Wanlin, VonerGy Technology Limited (Zhenjiang), Zhenjiang 212132, China. Journal of Chongqing University of Technology (Natural Science), 2024, 38(6): 30–38. doi:10.3969/j.issn.1674-8425(z).2024.06.004