Custom PFAS Free Hydrophobic Breathable Membrane For EV Battery Pressure Equalization

This custom PFAS-free hydrophobic breathable membrane is engineered for electric vehicle battery pack pressure equalization systems. It serves as the core barrier layer in battery vent units, allowing continuous pressure balance during altitude changes and thermal cycling, while completely excluding water, dust, and salt spray. The membrane is manufactured from high-temperature-resistant, non-fluorinated polymer and can be fabricated into custom discs, rolls, or integrated patches to suit specific battery pack vent designs. It aligns with the automotive industry’s shift toward PFAS-free materials.

EV battery packs are enormous sealed volumes that experience pressure swings of 15–25 kPa during mountain driving or rapid charging. Without proper venting, the pack housing deforms and seal durability is compromised. Current vent membranes are typically ePTFE, a PFAS substance. Automakers have announced target dates to eliminate PFAS from all vehicle components. A substitute membrane must offer equivalent protection and fire resistance, plus long-term reliability under automotive life cycles.

Our PFAS-free membrane is produced with a carefully controlled pore distribution and oleophobic treatment. It provides airflow sufficient to equalize a 100-liter pack within seconds, while its water entry pressure exceeds 80 kPa, well above IP67 and IP6K9K requirements. The material is tested at 125°C continuous and can withstand brief exposure to 150°C. It can be supplied as pre-cut discs for integration into metal or plastic battery vent bodies, and customized with adhesive edge sealing gaskets.

• Material: PFAS-free polyolefin with oleophobic coating
• Thickness: 0.20–0.45 mm
• Air permeability: 400–800 ml/min/cm² @ 70 mbar
• Water entry pressure: > 80 kPa
• Max continuous temp: 125°C
• Burst pressure support: compatible with burst disc integration
• Diameter: custom, 10–50 mm typical

Used in passenger EV battery enclosures, electric bus battery compartments, stationary energy storage containers, and high-voltage power electronics housings. It is designed for integration into threaded or snap-fit vent assemblies that may also include burst discs for emergency venting.

The membrane is clamped or bonded into the vent assembly. During normal operation, air flows bi-directionally to cancel out pressure differences caused by temperature or altitude changes. The oleophobic surface prevents oil and electrolyte mist from wetting the pores. In the event of a cell venting, the rapid pressure spike is managed by the burst disc, while the membrane continues to seal the housing from external water and dust.

Start with the required airflow derived from your pack’s sealed volume and maximum altitude change rate. Discuss the vent assembly design with our engineers to determine the membrane diameter and edge sealing method. If a burst disc is integrated, ensure the membrane’s burst-through resistance does not impede disc activation. We provide samples with adhesive ring pre-applied for quick prototyping.

Q: Is the oleophobic coating PFAS-free?

A: Yes, we use a non-fluorinated surface treatment. Oil repellency is achieved through hydrocarbon-based chemistry.

Q: Can I get this membrane with a conductive layer for EMI shielding?

A: We can laminate a conductive non-woven onto one side; however, the membrane core remains PFAS-free.

Q: How is the membrane fixed in a metal vent body?

A: By crimping or using a snap-ring. We can supply membranes pre-assembled into custom stainless steel retainer rings.