Publish Time: 2026-07-26 Origin: Site
When one EV battery cell enters thermal runaway, heat can spread to neighboring cells and turn a localized failure into a module-level fire.
The most effective passive solution is to place a validated aerogel insulation pad between adjacent cells or other critical heat-transfer paths. Aerogel provides high thermal resistance with relatively little thickness, making it attractive for compact, energy-dense EV battery modules.
Silica aerogel samples demonstrating the highly porous structure associated with thermal insulation performance. Image source: NASA Science[1].
Without an effective cell-to-cell thermal barrier, heat from a failed pouch or prismatic cell can reach the neighboring cell fast enough to trigger thermal runaway propagation.
Installing an aerogel pad between adjacent cells increases thermal resistance and slows conductive heat transfer. This gives the module more time to control the event through structural isolation, venting, cooling, electrical protection, and battery-management strategies.
A peer-reviewed 2023 study on nickel-rich lithium-ion battery modules measured a thermal conductivity of about 0.020 W/(m·K) for the tested silica aerogel sheet at room temperature. The researchers found that sufficient aerogel layering could suppress thermal runaway propagation in their specific pouch-cell module configuration.[2]
Aerogel is valuable because battery engineers are always fighting for millimeters. A thick conventional barrier can reduce usable pack volume, while a thin high-performance thermal barrier can help preserve energy density without leaving neighboring cells directly exposed to a runaway event.
If the insulation only delays heat for a few seconds but cannot keep the neighboring cell below its critical temperature, thermal runaway may continue through the entire module.
The correct goal is not simply to use aerogel, but to use enough validated thermal resistance for the real cell chemistry, state of charge, compression, and module geometry. Aerogel should be treated as part of a complete thermal propagation control system.
A 2025 Journal of Energy Storage study tested mechanically reinforced silica aerogel felt between ternary pouch cells. In that test configuration, 2 mm aerogel felt successfully prevented thermal runaway transmission, while a 1 mm sample delayed propagation but did not prevent it under the tested conditions.[3]
This does not mean that every EV battery requires a 2 mm pad. It shows why engineers should never choose aerogel thickness from a generic chart alone. Different cells can release very different amounts of heat during thermal runaway.
UL Solutions evaluates EV battery thermal propagation at cell, module, and pack levels and specifically considers the effectiveness of anti-propagation barriers and insulating materials. That testing approach reflects an important engineering principle: material data alone cannot prove battery-pack safety.[4]
Buying an aerogel pad only by thermal conductivity and price can cause compression failure, insufficient thermal protection, dimensional instability, or late-stage battery validation failure.
The correct solution is to specify thickness, thermal resistance, compression behavior, dielectric performance, dimensional tolerance, durability, and integration requirements together. The final pad must be validated under the real battery module conditions rather than only at room temperature.
Design Requirement |
What Engineers Should Verify |
Main Risk |
|---|---|---|
Thermal performance |
Thermal resistance under expected temperature and compression |
Neighboring cell heats too quickly |
Pad thickness |
Module-level thermal propagation performance |
Too thin to protect or too thick for pack space |
Compression behavior |
Cell swelling, compression set, fatigue, and dimensional recovery |
Changing cell pressure or thermal performance |
Electrical insulation |
Dielectric strength and insulation resistance where required |
Leakage or short-circuit path |
Vehicle durability |
Vibration, humidity, thermal cycling, fluids, abrasion, and particle shedding |
Performance degradation during vehicle life |
SAE J2464 provides abuse-testing guidance for electric and hybrid vehicle rechargeable energy storage systems at cell, module, and pack levels. It reinforces the need to evaluate battery-system behavior under conditions outside the normal operating range rather than relying only on material specifications.[5]
Aerogel also cannot replace vent design, cooling, fusing, current interruption, BMS monitoring, structural protection, or high-voltage isolation. Thermal runaway can transfer energy through cell surfaces, busbars, cooling plates, module frames, hot gases, flame, and electrical conductors.
Need an Aerogel Insulation Pad Sample for an EV Battery Module?
Send your cell chemistry, cell dimensions, available gap, target thickness, compression requirement, module drawing, thermal runaway validation target, and annual volume for a preliminary material and structure review.
Using a generic aerogel specification without module testing can create a false sense of safety and cause expensive redesign after thermal propagation testing.
Use these answers as an engineering starting point, then validate the final insulation structure in the actual battery module.
An aerogel pad increases thermal resistance between cells, slowing heat transfer from a failing cell and helping reduce the risk of cell-to-cell thermal runaway propagation.
No. Aerogel cannot prevent every cell failure. A properly designed barrier can help stop or delay propagation in a validated module, but battery safety still depends on cooling, venting, electrical protection, structure, sensors, and control strategy.
There is no universal thickness. The correct value depends on cell chemistry, energy, state of charge, spacing, compression, runaway severity, available package space, and the required propagation test.
Not in every application. Aerogel is attractive for high thermal resistance in limited space, while mica can provide strong electrical insulation and structural stability. Some EV battery designs combine multiple materials to achieve both thermal and dielectric protection.
It can, depending on the complete material construction. Engineers should verify the actual dielectric strength, surface layers, edge condition, thickness, moisture exposure, and operating voltage rather than assuming every aerogel pad provides the same electrical insulation.
Based on 15 years of automotive wire harness and EV electrical integration experience, I recommend evaluating the aerogel pad together with the battery cells, busbars, high-voltage harness, temperature sensors, cooling plate, connectors, fuse system, and enclosure. Thermal runaway does not follow only one path, so the safest battery module is the one validated as a complete electrical, thermal, and mechanical system.
For an aerogel insulation pad sample, battery thermal barrier review, prototype evaluation, or custom EV insulation project, provide your module drawing and technical requirements before freezing the material specification.
[1]NASA Science — Aerogel Samples
[4]UL Solutions — EV Battery Abuse, Fire and Thermal Propagation Testing
[5]SAE International — SAE J2464 RESS Safety and Abuse Testing