Preoxidized fiber composite aerogel mats used as fire-retardant and thermal-insulation pads inside power battery packs.

The preoxidized fiber-composite aerogel felt is a new type of high-performance flexible thermal insulation material formed by combining nano-porous aerogels with polyacrylonitrile (PAN)-based preoxidized fiber substrates through advanced composite technology.

In the pre-oxidized silk-based composite aerogel felt, silica (SiO₂) aerogel serves as the functional core material, effectively inhibiting air convection and reducing solid thermal conduction and thermal radiation to minimal levels. The pre-oxidized silk fiber felt acts as a reinforcing framework; pre-oxidized silk is an intermediate product obtained by pre-oxidizing PAN precursor fibers, and it boasts excellent thermal stability, flame retardancy, and superior mechanical strength. The fiber felt, produced via nonwoven processes such as needle punching, provides a robust yet flexible support structure for the fragile aerogel, significantly enhancing the composite’s processability, tensile strength, and impact resistance.

Characteristics of pre-oxidized silk composite aerogel felt:

① Excellent high-temperature thermal insulation performance
Its thermal conductivity at room temperature can be as low as approximately 0.018 W/(m·K). Under the same insulation performance, its required thickness is only one-fifth to one-third of that of conventional insulation materials such as rock wool and glass wool, thereby achieving highly efficient space savings. Importantly, its outstanding performance remains stable even at high temperatures. The product can operate continuously over a wide temperature range from -200℃ to 650℃; certain models enhanced through special processing can even withstand short-term flame exposure exceeding 1,000℃.

② Exceptional fire resistance and flame-retardant safety

The material itself is derived from inorganic silicon sources and flame-retardant preoxidized fibers, giving it inherently flame-retardant properties. When exposed to a fire source, it does not produce flaming combustion; instead, it may only undergo slow smoldering or carbonization. Moreover, it produces low smoke levels, effectively slowing the spread of fire and buying valuable time for evacuation and firefighting efforts.

③ Stable hydrophobic and breathable properties
Thanks to the nanoscale hydrophobic modification of aerogels, the composite felt exhibits a water-repellent effect similar to that of lotus leaves, preventing liquid water from penetrating deep into the material. This property enables the material to remain dry for extended periods in humid environments, without any degradation in its internal thermal insulation performance, and effectively safeguards against corrosion on the outer surfaces of pipes or equipment. Meanwhile, its nano-porous structure allows water vapor molecules to pass through, thereby eliminating the risk of internal condensation.

④ Significant weight reduction and ease of construction
With its low density, this material significantly reduces the additional weight of thermal insulation systems—a critical advantage for weight-sensitive applications such as aerospace and new-energy vehicles. The material is both flexible and easy to cut, bend, and wrap, allowing it to conform precisely to equipment and piping of various complex shapes. It’s simple to install, generates minimal waste, and can substantially lower labor costs and construction timelines. Moreover, on equipment requiring periodic maintenance, this material can be repeatedly disassembled and reused, offering even greater cost-effectiveness.

⑤ Environmental Protection and Durability
Next-generation production processes, such as water-based environmentally friendly technologies, are gradually replacing traditional processes that rely on hazardous chemical raw and auxiliary materials, thereby achieving environmentally friendly raw materials and low emissions throughout the production process, and enhancing the green attributes of the products. The composite structure also endows the material with excellent resistance to aging and fatigue, giving it a service life that far exceeds that of most organic thermal insulation materials.

Application fields of pre-oxidized fiber composite aerogel felt:

1. Aerospace and Defense sector

Thanks to its ultra-low density and exceptionally high thermal insulation efficiency, this material effectively shields aircraft from the high temperatures generated by atmospheric friction or from the extreme heat in engine compartments, while significantly reducing the structural load on the aircraft and enhancing its payload capacity and range. In defense applications, it is used for engine thermal insulation in specialized vehicles and thermal protection for ammunition storage facilities, meeting stringent reliability requirements even under extreme environmental conditions. It can also be employed as thermal insulation layers in aircraft engine nacelles, thermal protection linings for rocket engine nozzles, thermal shield components for hypersonic vehicles, and engine thermal shields for specialized armored vehicles. With its ultra-light weight and exceptional temperature resistance, this material can insulate against heat levels reaching thousands of degrees Celsius—generated by jet engines or rocket exhaust plumes—thereby protecting sensitive onboard instruments and the structural integrity of the aircraft’s cabin. In military vehicles, it helps reduce engine thermal radiation signatures, improving stealth capabilities and providing enhanced protection for personnel in the vicinity.

2. New Energy Vehicles and the Transportation Sector

In the thermal management systems of new-energy vehicles, particularly in pure electric vehicles, this material is used as a highly efficient thermal insulation and fire-retardant barrier for lithium-battery packs. It serves as fire-resistant and heat-insulating pads within power battery packs, thermal isolation sheets between battery modules, and lining materials for the top cover of battery packs. By slowing down the spread of heat during thermal runaway of individual battery cells, it provides passengers with more time to safely evacuate, making it one of the key materials for enhancing battery-pack safety. This material is also applied to thermal insulation of high-temperature components such as motors and electronic control units.

3. Energy-saving field for industrial pipelines and equipment

In fields such as petrochemicals, building materials and metallurgy, and industrial kilns, a large number of high-temperature pipelines, reaction vessels, and industrial furnace bodies require thermal insulation. Pre-oxidized fiber-composite aerogel mats are used as thermal insulation sleeves for high-temperature reaction pipelines and valves in the petrochemical industry; as cryogenic insulation layers for deep-cold LNG (liquefied natural gas) storage tanks and pipelines; as thermal insulation linings for high-temperature flue ducts and hot-air pipes in steel plants; and as removable thermal insulation garments for industrial flanges and elbows that require frequent maintenance. In areas where conventional insulation layers cannot be applied due to space constraints, wrapping with thin-layer aerogel mats can significantly reduce heat loss and improve energy efficiency. The material’s excellent hydrophobic properties effectively prevent corrosion of pipelines in humid environments. Its flexibility allows it to perfectly conform to complex components and facilitates easy removal and maintenance.

4. Architecture and Special Fire Protection Fields

In the construction sector, these materials can be used in applications with stringent fire protection and energy-saving requirements—such as exterior wall insulation and fire-separation systems for high-rise buildings, thermal insulation of indoor pipe shafts, fire-resistant sealing and wrapping materials for cable and pipe shafts in high-rise buildings, fire-retardant protective coatings for steel structures, thermal insulation linings for confined interior spaces in historically protected buildings, and thermal barriers for server cabinets in data centers. In urban district heating networks, their excellent water-repellent properties and long-lasting thermal insulation performance can significantly reduce heat loss from underground high-temperature steam or hot-water pipelines, while also addressing the corrosion challenges caused by pipeline dampness, thereby ensuring the long-term safe and economical operation of the heating network. When used to wrap cable and pipe conduits in building shafts, these materials effectively prevent flames and toxic fumes from spreading upward through the shafts in the event of a fire. Wrapping steel structures can delay the heating and softening of steel under fire conditions, helping to maintain the structural integrity of buildings.

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