Flame Retardant Foams

Battery encapsulation is the process of placing a protective material around or between battery cells and other module components. The material is typically dispensed as a liquid and cured in place to form a stable structure around the components.

Encapsulation can support thermal protection, electrical insulation and structural stability within an EV battery module. Depending on the material and module design, it may also help protect components from vibration, impact, moisture and other environmental exposure.

An encapsulant is dispensed into the spaces surrounding battery cells or components during assembly. It then cures or expands to fill the required area, helping to hold components in position and create a protective barrier within the module. The exact dispensing and curing process depends on the encapsulant chemistry and production requirements.

Encapsulation is commonly used around battery cells within a module, but it may also be used for connectors, electronic assemblies and other components that require protection. The application area depends on the cell format, module architecture and required level of structural, thermal or electrical performance.

A suitable encapsulant can help isolate an overheating cell and insulate adjacent cells from heat and flame. Its role is to help limit thermal propagation rather than allow a thermal event to spread freely through the module.

No single encapsulant can prevent every cause of thermal runaway. Encapsulation is one part of a broader battery safety and thermal-management strategy that may also include cooling systems, thermal interface materials, thermally conductive adhesives and dielectric coatings.

Yes, some encapsulants have structural or semi-structural properties that help unitize the module and hold cells in position. This can help the assembly withstand vibration, shock and other mechanical forces encountered during use.

The effect depends on the encapsulant’s thermal properties and its position within the module. Some encapsulants are designed to allow controlled thermal exchange while helping isolate an abnormal heat event. Encapsulation should therefore be evaluated as part of the complete thermal design, rather than as a standalone cooling solution.

Some battery encapsulants have dielectric properties that help electrically isolate components. However, electrical performance varies by formulation, so dielectric strength and the required insulation distance should be confirmed for the intended battery design.

An encapsulant generally fills a larger volume around cells or components and may provide insulation and structural support. A thermal interface material is primarily used to improve heat transfer between a heat source and a cooling surface. Structural adhesives bond components, while dielectric coatings provide a thinner layer of electrical isolation. These materials often work together within the battery pack.

The terms are often used together because both processes place a protective material around electrical component. In battery applications, “potting” may refer to filling a defined housing or cavity, while “encapsulation” can describe the broader process of surrounding cells or components. The terminology may vary by manufacturer and module design.

Battery encapsulants may be based on polyurethane, epoxy, silicone or other material technologies. Each chemistry offers a different balance of density, viscosity, hardness, flame retardancy, impact resistance, processing requirements and thermal or electrical properties.

Foam encapsulants can fill space around cells while adding less mass than some solid alternatives. Certain polyurethane foams are also designed to be self-leveling, flame retardant and resistant to vibration or impact. These characteristics are formulation-specific and should be confirmed using the relevant technical data.

Selection should consider the complete module design. Important factors may include:

• Flame-retardancy requirements
• Density and added module weight
• Viscosity and flow during dispensing
• Expansion and cure behaviour
• Hardness and compression modulus
• Electrical insulation
• Thermal performance
• Impact and vibration resistance
• Outgassing and exotherm
• Compatibility with cells, substrates and manufacturing equipment

Final suitability should be established through application-specific testing.

H.B. Fuller’s EV Protect portfolio includes liquid-applied, two-component polyurethane foam encapsulants for battery cells and modules. Available formulations provide different hardness and compression-modulus profiles, allowing engineers to evaluate options against their structural, processing and protection requirements. Product selection should be based on the intended design, production process and validation testing.