Comprehensive analysis of 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
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
ParameterRequirementTypical Value
HardnessShore A 30-60Per design
Tensile strength≥ 7 MPa7-10 MPa
Elongation at break≥ 300%300-600%
Compression set≤ 15% (150°C×22h)8-15%
Dielectric strength≥ 20 kV/mm20-25 kV/mm
Flame retardancyUL94 V-0V-0
Thermal conductivity1.0-3.0 W/m·KPer formulation
Temperature range-40°C to 150°CCompliant
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.
