Publish Time: 2026-09-20 Origin: Site
Choosing an EV battery thermal runaway barrier by maximum temperature alone can leave the pack vulnerable to cell-to-cell propagation, flame jets, particle erosion or electrical failure.
The correct material depends on where the barrier is installed and what it must do during both normal battery operation and a thermal event. Aerogel is particularly attractive for thin cell-to-cell thermal resistance, mica provides robust electrical and high-temperature insulation, while ceramic composite materials can provide strong fire and thermal protection in module and pack-level applications.
There is therefore no universal winner in the aerogel vs mica comparison. A battery engineer should first define thermal exposure, thickness, compression, dielectric requirements and installation location before selecting the material.
Replacing one material with another on thermal conductivity alone can solve one problem while creating a packaging, compression or electrical-insulation problem.
Compare the materials by function rather than material name. Aerogel can provide high thermal resistance in a thin cell-to-cell space; mica is widely suited to electrical insulation and fire-resistant barriers; ceramic-based composites become attractive where severe thermal exposure and structural barrier performance matter.
Material | Strong Application | Design Issue to Check |
|---|---|---|
Aerogel | Cell-to-cell thermal barrier | Compression, thickness and integration |
Mica | Electrical and high-temperature insulation | Formability, edges and installation geometry |
Ceramic Composite | Fire and thermal protection | Thickness, flexibility and manufacturing method |
Using a barrier that conducts too much heat across a narrow cell gap can allow a failed cell to heat its neighbor fast enough to contribute to propagation.
Aerogel becomes especially interesting where high thermal resistance must fit into a thin cell-to-cell space. Commercial EV aerogel barriers can also be engineered around compression behavior so the pad performs during normal cell swelling as well as during an abnormal thermal event.[1]
Aspen Aerogels has reported a mini-module example using two 62 Ah prismatic cells with a 2.35 mm PyroThin barrier at roughly 50% strain. The adjacent cell did not enter thermal runaway in that specific test, although Aspen explicitly notes that the setup isolated some secondary propagation pathways found in a complete pack.[2]
That result should not be converted into a universal “2.35 mm aerogel rule.” Cell chemistry, energy, spacing, compression and propagation mechanisms differ by battery design.
Using a soft cell-compression material everywhere can leave busbars, module boundaries or pack covers without the electrical or structural barrier they require.
Use mica or ceramic composite materials where the design needs high-temperature electrical insulation, fire resistance or a more structurally stable barrier. Mica can be particularly useful around HV conductors, busbars, module structures and pack-level insulation.
Ceramifiable silicone composites provide another route. Saint-Gobain, for example, lists ceramifiable silicone products for cell-to-cell thermal runaway pads and pack protection, demonstrating that a ceramic-forming system can combine flexibility during assembly with a protective barrier during severe heat exposure.[3]
Buying the material with the most impressive temperature claim does not prove that the battery pack will resist thermal propagation.
Define the actual failure exposure and validate the finished construction. Consider cell chemistry, barrier location, available thickness, compression, dielectric performance, flame exposure, particle impact and adjacent materials.
UL Solutions notes that a thermal runaway event can involve high temperature, pressure, jet-like flames and ejected particles capable of eroding protective materials. UL 2596 testing was developed to screen material performance against these combined hazards.[4]
Comparing Mica, Aerogel and Ceramic Battery Barriers?
Send Fuqiang your cell format, barrier location, available thickness, compression requirement and thermal protection target. Our engineering team can review die-cut material options and prepare prototype samples for battery-pack validation.
Not universally. Aerogel is particularly useful for thin cell-to-cell thermal barriers, while mica can be advantageous where electrical insulation, structural stability and high-temperature protection are priorities.
Depending on the application, alternatives can include aerogel barriers, ceramifiable silicone composites and other ceramic-based insulation systems. The replacement must be selected by function rather than thickness alone.
A barrier does not stop the electrochemical failure inside the initiating cell. Its role is to reduce heat and other propagation pathways so neighboring cells are less likely to enter thermal runaway.
There is no universal best material. Cell chemistry, available gap, compression, thermal exposure and pack architecture determine the appropriate barrier.
Yes. A pack can use aerogel between cells and mica or other high-temperature insulation at module, busbar or enclosure locations when the engineering requirements justify a hybrid material strategy.
A 15-Year Automotive Wire Harness and EV Insulation Perspective
After 15 years working around automotive wire harnesses and EV electrical insulation, I have learned that thermal runaway protection should be designed by location and failure mode, not by material reputation. The strongest battery packs often use different materials for cell-level thermal resistance, HV electrical insulation and pack-level fire protection.
[1] Aspen Aerogels — PyroThin Cell-to-Cell Thermal Runaway Barriers
[2] Aspen Aerogels — Cell-to-Cell Thermal Propagation Testing
[3] Saint-Gobain — EV Battery Fire and Thermal Propagation Protection
[4] UL Solutions — Battery Enclosure Thermal Runaway Evaluation