As EV batteries and energy storage systems become more compact and energy-dense, thermal runaway protection has become an important consideration in battery design. Traditional insulation materials may provide thermal or electrical insulation, but demanding applications often require fire resistance, thermal insulation, flexibility and cushioning in one material.
Ceramicized silicone foam is developed for this type of application. It combines the flexibility of silicone foam with a ceramic-forming protective mechanism that becomes active under extreme heat.
Ceramicized silicone foam is a closed-cell silicone foam designed to provide thermal insulation, electrical insulation, flame resistance and cushioning.
Under normal operating conditions, the material remains flexible and compressible. When exposed to extreme heat or flame, its ceramic-forming components react and create a rigid, ceramic-like protective layer.
This transformation helps create an additional barrier against flame penetration, heat transfer and thermal propagation.
Recent research has demonstrated that ceramifiable silicone foams can form a dense ceramic barrier during thermal exposure and can be used to limit thermal runaway propagation in battery modules.
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Thermal runaway in lithium-ion battery cells can release high-temperature gases, molten particulates, and intense direct flames within seconds. Without an effective thermal barrier, adjacent cells absorb this extreme heat, triggering domino-style thermal propagation across the entire pack.
Integrating ceramicized silicone foam provides multi-functional protection during both regular operations and catastrophic events:
| Protection Aspect | Function in EV Battery Systems |
|---|---|
| Thermal Insulation | Slows localized heat conduction between cells, preventing neighboring cells from reaching critical thermal runaway threshold temperatures. |
| Flame Resistance | Resists direct flame blowthrough, maintaining structural integrity under continuous high thermal exposure. |
| Electrical Isolation | Prevents electrical arcing, short circuits, and high-voltage breakdown between closely packed battery cells and enclosure walls. |
| Mechanical Cushioning | Absorbs shock, road vibration, and accommodates natural volumetric expansion (swelling) during charge-discharge cycles. |
| Sealing & Gap Filling | Fills tolerances between structural components, blocking the bypass route of hot gases and moisture. |
The core mechanism of ceramicized silicone foam is its two-stage temperature response, transitioning from a flexible polymer matrix into a self-supporting ceramic structure under high thermal stress.
| Operating Stage | Material State & Reaction | Primary Protection Output |
|---|---|---|
| Normal Working Condition (< 200°C) |
Flexible closed-cell silicone matrix containing mineral additives and ceramifying agents. | Provides compression recovery, low thermal conductivity, dust/water sealing, and vibration damping. |
| Thermal Reaction Threshold (300°C - 500°C) |
Silicone polymer matrix begins pyrolyzing; ceramic fillers react at contact points to begin inorganic bonding. | Absorbs heat energy during chemical transformation, slowing temperature rise across the material thickness. |
| Ceramicized Stage (> 600°C Flame Exposure) |
Forms a dense, hard ceramic shell with high thermal resistance and mechanical integrity. | Blocks direct flame penetration, maintains physical spacing between components, and stops thermal propagation. |
Combining mechanical flexibility with high-temperature resistance gives ceramicized silicone foam distinct functional advantages over traditional insulation materials:
| Performance Feature | Technical Advantage |
|---|---|
| 1. Low Thermal Conductivity | Closed-cell cell structure traps air pockets, creating an efficient barrier against heat transfer between adjacent modules. |
| 2. High Flame Resistance | Meets stringent flame-retardant standards without releasing toxic smoke, forming a protective barrier when subjected to intense direct flame. |
| 3. High Dielectric Strength | Maintains reliable electrical insulation properties in high-voltage battery enclosures, reducing short-circuit risks under stress. |
| 4. Compression & Recovery | Exhibits low compression set, allowing the material to maintain sealing pressure and absorb structural tolerance variations over long operational lifespans. |
| 5. Active Thermal Protection | Transitions from an elastic pad to a hard ceramic barrier during thermal events, supplying emergency protection without increasing initial weight or volume. |
Due to its balance of mechanical flexibility and flame barrier capabilities, ceramicized silicone foam is utilized across critical safety assemblies:
| Application Area | Specific Material Function |
|---|---|
| EV Battery Packs | Used as intercell compression pads, module separators, pack perimeter seals, and thermal runaway barriers under battery top covers. |
| Energy Storage Systems (ESS) | Installed between stationary battery racks, cabinet containment walls, and internal busbar insulation partitions to manage thermal containment. |
| Automotive Electronics | Applied around electric vehicle power distribution units (PDU), junction boxes, and control units to protect sensitive electronics against thermal spikes. |
| Electrical & Power Equipment | Serves as fire-stop gasketing, cable penetration seals, and insulating layers in commercial electrical enclosures and high-voltage equipment. |
| Feature | Conventional Silicone Foam | Ceramicized Silicone Foam |
|---|---|---|
| Thermal insulation | ✓ | ✓ |
| Flexible cushioning | ✓ | ✓ |
| Electrical insulation | ✓ | ✓ |
| Flame resistance | Grade dependent | Enhanced |
| Ceramic barrier formation | — | ✓ |
| Thermal runaway protection | Limited | Designed for this application |
| EV battery application | ✓ | ✓✓ |
The main advantage is not simply higher temperature resistance. It is the ability to combine flexible foam performance with an additional ceramic barrier during extreme heat exposure.
Proper material selection requires matching physical and thermal parameters with internal battery pack design constraints:
| Parameter | Selection Criteria | Application Impact |
|---|---|---|
| Density | Select lower density for lightweight cushioning; select higher density for structural loading and firmer gap filling. | Affects total battery pack weight and mechanical support stiffness. |
| Thickness | Match available tolerance gaps and target thermal conduction delay times. | Determines thermal barrier performance and internal space utilization. |
| Compression Force Deflection (CFD) | Evaluate required force to compress foam to a given percentage (e.g., 25% or 50%). | Ensures sufficient continuous pressure without over-stressing battery cell casings. |
| Flame Rating | Verify compliance with industry safety standards like UL 94 V-0 or equivalent automotive specifications. | Guarantees self-extinguishing behavior and thermal containment compliance. |
| Dielectric Strength | Review breakdown voltage ratings under operating temperatures. | Prevents electrical leakage and shorting between modules. |
To integrate ceramicized silicone foam into high-volume manufacturing lines, components can be customized into ready-to-assemble formats:
| Supply Format | Fabrication Details |
|---|---|
| Precision Die-Cut Parts | Custom-stamped profiles matching exact cell dimensions, busbar cutouts, or pack perimeter channels. |
| Adhesive Backing (PSA) | Laminated with single or double-sided heat-resistant pressure-sensitive adhesives for rapid positioning during assembly. |
| Composite Laminates | Combined with fiberglass cloth, polyimide films, or metallic foils to improve tensile strength or tear resistance. |
| Sheets & Continuous Rolls | Provided in continuous roll format or cut sheets for secondary processing and custom cutting. |
Ceramicized silicone foam provides a practical combination of thermal insulation, flame resistance, electrical insulation, cushioning and ceramic barrier formation.
For EV batteries and energy storage systems, its main value is the ability to remain flexible during normal operation while creating an additional protective barrier when exposed to extreme heat.
If you are developing an EV battery, ESS, high-voltage electrical or thermal protection application, the appropriate ceramicized silicone foam should be selected according to density, thickness, compression performance, thermal requirements and flame rating.
Need help selecting the right material? Contact us with your required thickness, density, dimensions and application. We can recommend a suitable ceramicized silicone foam solution for your project.
