LSR Silicone Sealing for EV Battery Packs

LSR Silicone Sealing Solutions for New Energy Vehicle Battery Packs

The rapid development of new energy vehicles has placed unprecedented demands on battery pack safety and reliability. As the core energy unit of the vehicle, battery pack sealing directly relates to battery safety, vehicle performance, and passenger protection. LSR silicone sealing components serve three critical functions in battery packs: IP protection, thermal management, and electrical insulation.

I. Core Challenges in Battery Pack Sealing

1. IP Protection Requirements

• Battery packs require IP67 or IP68 protection rating
• Prevent water, dust, and salt spray intrusion causing battery short circuits
• Must remain effective during vehicle wading and car wash scenarios

2. Thermal Management Needs

• Battery operating temperature window: 15-35°C
• Charging/discharging temperatures can reach 60°C; thermal runaway exceeds 150°C
• Seals must withstand -40°C to 150°C temperature range

3. Electrical Safety

• Battery pack internal voltage: 400-800V
• Dielectric strength ≥ 20 kV/mm, volume resistivity ≥ 1×10¹⁵ Ω·cm
• Flame retardancy: UL94 V-0 rating

4. Mechanical Loading

• Bolt compression: 15-30% compression on sealing strip
• Vibration and impact loads during driving
• Cell swelling compensation during charge/discharge cycles

II. LSR Sealing Solution Design

1. Battery Pack Lid Seal

• Rectangular cross-section seal strip along lid perimeter
• Compression design: 20-25%, ensuring contact pressure ≥ 1.5 N/mm
• LSR hardness Shore A 40-50, balancing sealing and compression set
• In-mold one-piece forming, no splices, eliminating traditional rubber strip joint leakage points

2. Inter-Module Seals

• Flexible gaskets compensating for manufacturing tolerances between modules
• Thickness 2-5mm, uniform gap filling after compression
• Thermally conductive LSR (1.0-3.0 W/m·K) for combined sealing and heat conduction

3. Junction Box/BDU Seals

• Precision seals mating with connector housings
• Multi-chamber design isolating signal and power cables
• Dielectric strength and flame retardancy as primary specifications

4. Explosion-Proof Valve Seals

• Waterproof breathable membrane + LSR seal ring combination
• Pressure relief during thermal runaway, water blocking during normal operation
• Valve opening pressure: 2-10 kPa (designable)

III. Material Property Requirements

IV. Manufacturing and Quality Control

1. In-Mold Forming

• Battery pack lid seals up to 2-4 meters long, one-piece in-mold forming
• Mold precision ±0.05mm, ensuring seal cross-section consistency
• Vulcanization: 170°C × 60-90 seconds

2. Metal Insert Overmolding

• Junction box seals often include metal inserts
• Insert preheated to 150°C for strong LSR bonding
• Pull test: insert-to-LSR bond strength ≥ 50N

3. Dimensional Inspection

• Seal cross-section optical inspection
• Compression force vs. deformation curve measurement
• Critical dimensions CPK ≥ 1.33

4. Seal Integrity Verification

• Air tightness test: 0.5 bar positive pressure for 5 minutes, leak rate ≤ 0.1 mL/min
• IP67 immersion test: 1m depth for 30 minutes, no water ingress
• Post thermal cycling seal integrity re-verification

NEV battery pack LSR sealing solutions are the critical safeguard for battery safety and reliability, requiring systematic control from materials through design to manufacturing across the entire chain.