What Type of Foam is Used in Power Battery Cells?

In battery cells of new energy electric vehicles (NEVs), the foam can act as a heat-insulating buffer when the cells expand and contract due to heat . When the cells experience thermal runaway, the foam can prevent the transfer of heat and has flame-retardant properties. In the battery pack, located below the liquid cooling plate or next to the upper and lower box covers, the foam can provide support and shock absorption . It can also be used as a battery sealing ring. Foam materials play a critical role in ensuring the safety, thermal management, and flame-retardant of power battery packs.

Why Foam is Critical in NEV Power Batteries?

·Thermal Insulation & Safety: Prevent heat transfer between cells, delaying thermal runaway and reducing fire risks.

·Stress Absorption: Battery cells expand and contract during operation. Foam absorbs mechanical stress, preventing cell damage and prolonging battery life.

·Flame Retardancy: High-performance foams (e.g., UL94 V-0 silicone) slow down fire spread, providing critical escape time in case of thermal incidents.

·Sealing & Waterproofing: Ensures IP67/IP68 protection, keeping moisture and dust out of battery packs.

·Vibration Damping & Structural Support:Reduce vibrations from road impacts, protecting battery integrity and improving vehicle NVH (Noise, Vibration, Harshness).

Types of Foam Commonly Used between Power Battery Cells

1.Polyimide Foam (PI Foam)

Benefits of Polyimide Foam: Extremely low thermal conductivity (<0.033 W/m·K), excellent fire resistance (self-extinguishing), and high-temperature stability.

Common Applications: Used for thermal insulation between cells to prevent thermal runaway propagation. It also absorbs stress from cell expansion and contraction during charge/discharge cycles.

2.Silicone Foam

Benefits of Silicone Foam: High flame retardancy (UL94 V-0), waterproof, and excellent compression resilience.

Common Applications: Used in battery sealing, liquid cooling plate support, and cushioning between cells. Ultra-thin silicone foam (as thin as 0.6mm) is now available, providing lightweight yet highly flame-resistant solutions.

3.Polyurethane Foam (PU Foam)

Benefits of Polyurethane Foam: Low hardness with high rebound, good shock absorption, and durability.

Common Applications: Used in soft-pack and prismatic lithium-ion batteries for structural buffering and vibration damping.

4.Ethylene-Vinyl Acetate (EVA) Foam

Benefits of EVA Foam: Good cushioning and insulation properties, cost-effective.

Common Applications: Often used in battery pack support structures and shock absorption layers.

5.Microcellular Polyurethane Foam (Norseal® PF Series)

Benefits of Microcellular Polyurethane Foam: Long-term compression resistance, high flame retardancy, and thermal stability.

Common Applications: Ideal for flexible battery pack designs requiring both cushioning and thermal management.

Key Considerations When Choosing Foam for Automotive Seats

While foam in batteries focuses on safety and thermal management, automotive seat foam prioritizes comfort and durability. Key factors include:

·Density & Firmness: High-density foam offers better support, while softer foam enhances comfort. Sports cars often use firmer foam for better body support, while luxury vehicles prefer softer foam for a plush feel.

·Material Type: Different type of materials have different effects, For example,

  Polyurethane (PU) Foam: Most common, balances comfort and cost.

  Memory Foam: Adapts to body shape, reducing fatigue on long drives.

  Latex Foam: Natural, breathable, and durable but more expensive.

·Breathability & Heat Resistance: Open-cell foams improve airflow, reducing sweat buildup in summer. Some seats integrate cooling gel layers for enhanced comfort.

·Longevity & Compression Resistance:High-quality foam resists sagging over time, maintaining seat shape even after years of use.

Conclusion

Foam materials are indispensable in NEV power batteries, ensuring thermal safety, mechanical stability, and longevity. Polyimide, silicone, and polyurethane foams dominate due to their flame resistance, stress absorption, and sealing properties. Meanwhile, in automotive seating, foam selection revolves around comfort, durability, and ergonomic support. As NEV technology evolves, advanced foams will continue to enhance both battery safety and passenger comfort, driving the future of electric mobility.