Application of Pre-oxidized Fiber Aerogel Felts in New Energy Vehicle Batteries

With the rapid growth of the new energy vehicle (NEV) industry, the safety, lightweight design, and adaptability of power batteries to extreme environments have become core requirements for industrial upgrading. In the realm of battery material innovation, pre-oxidized fiber aerogel felts—which combine the high-temperature resistance and flame retardancy of pre-oxidized fibers with the superior thermal insulation properties of aerogels—achieve a synergistic effect ("1+1>2"). This composite material overcomes the performance limitations of traditional battery protection materials, offering indispensable value in critical areas such as power battery thermal management and safety protection. This article explores the core composite characteristics of pre-oxidized fiber aerogel felts, analyzes their specific applications and technical advantages within NEV battery packs, and provides an outlook on their future development.

I. Core Composite Characteristics of Pre-oxidized Fiber Aerogel Felts: Meeting the Key Requirements of Power Batteries

Pre-oxidized fiber aerogel felt is a flexible thermal insulation material composed of pre-oxidized fibers and aerogel. The pre-oxidized fibers serve as a skeletal framework, providing structural support and a foundation for flame retardancy, while the aerogel acts as the primary insulating medium, delivering exceptional thermal insulation performance. The synergy between these two components results in a set of core characteristics well-suited to the operating environment of power batteries. First, it offers exceptional thermal insulation performance. The thermal conductivity of pre-oxidized fiber aerogel felt can be as low as 0.018–0.024 W/(m·K)—far superior to traditional insulation materials like glass wool or rock wool—enabling highly efficient thermal resistance even with a very thin profile. Second, it provides outstanding high-temperature resistance and flame retardancy. Leveraging the properties of pre-oxidized fibers—which can withstand long-term exposure to temperatures of 250°C–300°C without melting or dripping—combined with the inherently inorganic, heat-resistant nature of aerogels, this composite material maintains its structural integrity in environments up to 800°C. With an oxygen index exceeding 45%, it is classified as a non-combustible material, perfectly meeting the critical requirements for thermal runaway protection in power batteries. Third, it offers significant lightweight advantages; with a density of only 0.12–0.18 g/cm³—much lower than that of traditional protective materials like metals or ceramics—it helps substantially reduce battery pack weight, thereby extending vehicle range. Fourth, it exhibits excellent flexibility and process adaptability. It can be cut and bent to accommodate the complex structures of battery packs, fitting easily into irregular spaces such as the inner surfaces of the casing or the gaps between modules. Furthermore, it possesses superior chemical corrosion resistance, protecting against damage from potential electrolyte leaks and ensuring long-term operational stability.

II. Specific Application Scenarios for Pre-oxidized Fiber Aerogel Felt in New Energy Vehicle Batteries

(I) Core Thermal Runaway Protection Layer for Battery Packs: A Critical Barrier Against Thermal Propagation

Thermal runaway represents the most severe safety risk for power batteries. When a battery experiences a rapid temperature surge—triggered by issues such as overcharging, short circuits, or physical impact—it can initiate a chain reaction, including electrolyte decomposition and the deintercalation of lithium ions from the cathode. This process releases a massive amount of heat (with instantaneous temperatures potentially exceeding 600°C) along with toxic gases, creating a high risk of fire or explosion. With its exceptional thermal insulation and high-temperature resistance, pre-oxidized fiber aerogel felt serves as a critical protective material for preventing thermal propagation. It is primarily used for fire-resistant barriers between battery modules, insulation layers inside battery pack enclosures, and protective shielding around explosion-proof valves. When placed between battery modules—in thicknesses of only 3–5 mm—this material effectively blocks the intense heat released by a module experiencing thermal runaway, reducing heat transfer by over 80%. This prevents fire from rapidly spreading to adjacent modules, buying precious time for vehicle occupants to escape, for the Battery Management System (BMS) to trigger warnings, and for emergency cooling measures to be deployed. Lining the interior of a battery pack enclosure with this material helps mitigate the impact of cold external temperatures on battery activity during winter (thereby improving range in cold weather) while also containing internal heat during a thermal runaway event, preventing the vehicle’s metal bodywork from deforming or catching fire. Furthermore, applying this material around explosion-proof valves helps contain high-temperature flames and toxic gases when the valves open to release pressure, reducing the risk of damage to other vehicle components and harm to occupants, ultimately enhancing the overall safety of the battery pack.

(II) Auxiliary Thermal Insulation for Battery Pack Thermal Management Systems: Improving Temperature Control Efficiency and Range

The performance and lifespan of power batteries are highly dependent on a stable operating temperature (ideally between 25°C and 40°C). Exposure to extreme heat in the summer or freezing cold in the winter can lead to battery capacity degradation, reduced driving range, and increased energy consumption. Thanks to its superior thermal insulation properties, pre-oxidized fiber aerogel felt can function as an auxiliary insulation material within a battery pack’s thermal management system—for instance, by wrapping HVAC heat-exchange channels or providing insulation for the bottom and side walls of the battery pack. In summer, applying pre-oxidized fiber aerogel felt to the side walls and base of a battery pack effectively blocks external heat—whether from solar radiation or conduction from the road surface—from entering the pack. This reduces the cooling load on the air conditioning system, thereby conserving battery energy that would otherwise be consumed for temperature control. In winter, the material can be used to wrap the battery pack’s heat-exchange piping, minimizing heat loss from the coolant. This enhances the heating efficiency of the PTC (Positive Temperature Coefficient) heater, shortens the time required for battery preheating, and reduces the battery’s own heat loss, helping to maintain battery activity in low-temperature conditions. Experimental data indicates that implementing comprehensive thermal insulation for battery packs using pre-oxidized fiber aerogel felt can increase vehicle range by 10%–15% in cold environments (-20°C) and by 5%–8% in high-temperature environments (above 35°C).

(III) Thermal Insulation and Electrical Insulation for High-Voltage Harnesses and Battery Tabs: Mitigating the Risk of Localized Overheating

Within the battery packs of new energy vehicles, components such as high-voltage harnesses and battery tabs can generate localized heat during high-load charging and discharging. Furthermore, there is a risk that insulation failure could lead to short circuits. Pre-oxidized fiber aerogel felt—which offers thermal insulation, electrical insulation, and flame-retardant properties—can be processed into thin sheets or sleeves, making it suitable for wrapping high-voltage harnesses and protecting the base areas of battery tabs. Encasing high-voltage wire harnesses in pre-oxidized fiber aerogel felt sleeves not only prevents heat generated during operation from spreading to adjacent battery cells—thereby avoiding localized high temperatures that could impair battery performance—but also serves as a superior alternative to traditional PVC insulation. This enhances both the electrical insulation and high-temperature resistance of the harnesses, mitigating the risk of insulation failure caused by aging or exposure to extreme heat. Furthermore, applying a thin layer of pre-oxidized fiber aerogel felt at the base of battery tabs provides isolation from metal components, such as module brackets. This prevents short circuits resulting from vibration-induced wear, while simultaneously blocking the transfer of heat from the battery cells to the tab connections—preventing increased contact resistance due to high-temperature oxidation and ensuring stable battery charging and discharging.

(IV) Battery Pack Protection for Specialized Scenarios: Adapting to Extreme Environments

For new energy vehicles operating in extreme environments—such as high-temperature desert regions, frigid cold climates, or mining sites—battery packs face significantly more rigorous protection requirements. The ability of pre-oxidized fiber aerogel felt to withstand extreme conditions makes it well-suited for these specialized applications. In high-temperature desert regions, installing a thickened layer of pre-oxidized fiber aerogel felt atop the battery pack enhances thermal insulation against direct sunlight, preventing internal temperatures from surging above 60°C. In frigid, cold regions, encasing the entire battery pack in this material creates an efficient thermal barrier that minimizes heat loss, working in tandem with the thermal management system to maintain a constant battery temperature. For vehicles used in mining or construction—where collisions are more likely—applying pre-oxidized fiber aerogel felt to the bottom and front of the battery pack provides a cushioning effect during minor impacts. Additionally, in the event that a collision leads to localized overheating, the material acts as a rapid barrier to contain the spread of heat, thereby reducing safety risks.

III. Application Challenges and Future Development Directions

Although pre-oxidized fiber aerogel felts offer significant advantages for batteries in new energy vehicles (NEVs), several challenges remain regarding their application. First, production costs are high; the complex manufacturing process for aerogels results in prices far exceeding those of traditional thermal insulation materials, which limits their large-scale adoption in entry-level and mid-range vehicle models. Second, the stability of the material’s fit under long-term vibration—a condition inherent to vehicle operation—requires improvement. Continuous vibration can cause gaps to form between the material and the battery pack housing or modules, thereby compromising thermal insulation performance.

Looking ahead, as aerogel manufacturing processes evolve (e.g., through the widespread adoption of ambient-pressure drying technology) and production scales up, the costs of pre-oxidized fiber aerogel felts are expected to decline, potentially enabling their use across all vehicle segments. Furthermore, the development of advanced composite bonding technologies could enhance the material’s adhesion to battery pack structures, ensuring greater reliability over long-term use. Additionally, in line with the industry trend toward "lightweight and integrated" NEV designs, pre-oxidized fiber aerogel felts could be combined with battery pack housing materials to create integrated solutions that provide both thermal insulation and structural support. This would further reduce battery pack weight and increase energy density. As technological breakthroughs continue, pre-oxidized fiber aerogel felts are poised to become a core material for safety protection and thermal management in NEV power batteries, providing robust support for the high-quality development of the industry.